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Hydrogen Seals and Tilt Pad Bearing Upgrades

How to improve aging GE Large Steam Turbine-Generators

Many large steam turbine-generators still in operation today have equipment that was designed over 50 years ago. Having stood the test of time is a testament to the quality of these designs, but that does not mean improvements aren’t available.


What can be done to improve the H2 sealing process?

Many GE Generators in service today use hydrogen seals that were developed in the 1930s. The seals consist of four 90° bronze segments that are held in place by garter springs. Pressurized seal oil pushes the two rings axially and in opposite directions making face sealS with the housing. With this design, there were many areas where hydrogen leaks can develop:

(1) At the "butt" joints between the ring segments.

(2) Between the faces of the seal rings and the faces of the housings.

(3) Through the static joints of the top and bottom halves of the main seal housing.

Note that there is always some gas loss via absorption of H2 into the seal oil that flows through and lubricates the seals rings.

Given that Hydrogen cooling is here to stay, the question is: What can be done to improve the H2 sealing process? In an ideal world, the GE hydrogen seal design should work reasonably well. In practice, the quarter-segment seal rings do not stay seated at the "butt joints", particularly if there is significant rotor vibration or if the seal ring housing is not centered on the rotor.

The hydrogen seal ring design used by TRI has 360-degree steel and Babbitt rings with bolted joints. Access to the rings is achieved by removing only a small top half housing and the main housing stays in place. "Hook" fits on the seal rings are gone, so these seals can easily be removed and inspected or replaced if necessary. Improvements to the design, materials and manufacturing keep the TRI hydrogen seal bores round and the joint gaps closed.


The Hydrogen Seal Retrofit Process

1. Prepare a drawing with an estimated size of the existing Hydrogen seal assembly.

Prepare modifications to show the upper outer removable housing to be added.

Obtain materials for the housing for each end and for the mating seal rings.

Rough machine the new removable housings to "near shape".

Process the seal rings through the Babbitting process.

When the outage starts, receive the existing end shields. Finalize drawings.

Modify the main Hydrogen seal housing, both upper and lower halves.

8. Semi-finish machine the upper outer removable seal housing.

9. Complete the machining of the details such as dowel pins and the like, and then the seal housing assemblies, including inspection for flatness.

10. Complete machining of the seal rings to TRI's recommended seal bore diameters, with inspection for flatness.

11. Pack and ship to site.

12. The re-installation process is so much simpler than disassembly that customers typically do not request Technical Direction from a TRI Representative, though such assistance is available.

TRI designs and manufactures complete hydrogen seal assemblies.

This permits the "Air Side" seals with slightly longer axial length to reduce seal oil flow out of the generator and permits higher pressures in the hydro-dynamic oil films which will minimize seal ring wear.

Tilt Pad Bearing Upgrades

The "classic" 6-pad tilting pad bearings of the GE Large Steam Turbines that were built between late 1950s through 2000 era (as well as other varied tilting pad bearings for Combined Cycle Gas Turbines including the D-11 Steam Turbines of more recent vintage) typically developed excessive wear patterns in the contact areas on the backs of the pads and on the mating surfaces of the housing bores. This applies to GE-style Tilting Pad Bearings with bores diameters from 8 inches to 24 inches.

While the Babbitt surfaces may be fine, the wear patterns on the backs of the pads can be large enough to cause the pads to have limited ability to roll, tilt, or twist as required by the design. The consequence is that they do not permit rolling well enough to be able to suppress sub-synchronous rotor vibration, including steam-whirl, one of the most damaging forms of sub-synch rotor vibration.

TRI has demonstrated the Engineering Skills to evaluate each tilting pad bearing situation, as well as to have a shop with the skilled manpower and specialized tooling necessary to refurbish the various bearing designs in an expeditious manner. Critical worksteps of these refurbishment processes are to bore out the housing and to machine a double radius curvature on the backs of the pads. The double radius curvature is critical because it allows the pads to roll, tilt, and twist correctly. Each pad must be able to move properly in order for the oil film to suppress the "cross-coupled" stiffness and damping characteristics that leads to sub-synchronous rotor vibration. If the contact surfaces are not refurbished, then even the best job of rebabbitting and remachining the bore is useless. If the pads cannot move properly, then the pads act as if they are a fixed bore bearing and this can lead to sub-synchronous rotor vibration. If in doubt, turn over the pads and look at the back side.

The 6-pad "classical" design

In many cases, the pad backs have worn a pocket into the bore of the housing. The pads and housings are made of very soft steel, and inserts have been made to fit into the back of the pads, not particularly the bottom pads. The top pads usually have a bar of soft steel across each pad to be used to adjust clearance.

In other cases, the bottom three pads have had bars installed that resemble the bars on the top pads, and these have been hand rounded so that they have a double curvature, but not a curvature that is sufficiently correct to produce the desired rolling function.

A problem with bottom pads that have had a slot cut for a bar is that this greatly reduces the bending stiffness and strength of the pad for supporting the oil film with a heavy load. TRI can offer other viable options, if time to obtain other materials exists.

Limited Options

Preferred options include making pad rings of heat-treated alloy steel and installing round inserts of similar steel in the top pads for clearance adjustments. Another variation is to install round inserts of heat-treated steel at all pad locations to resist wear.

In some cases, it appears that GE has made some new "classic" bearings with the latter insert feature for some of the high MW Steam Turbines.

In any of these cases, the preferred choice is to machine the back of the pads with a proper double radius shape. 

Exposure to GE Gas Turbine and D-11 Steam Turbine Bearings

During recent exposures to refurbishing bearings for GE Gas and Steam Turbines, generally associated with combined cycle plants, it appears that the tilting pad bearings have been produced with only initial cost in mind. Maintenance, operational considerations and reliability have unfortunately not been in primary focus as was the case years ago.

In any event, TRI clearly can refurbish these bearings, whether four or six pads, load on pivot, or load between pivots. An over-riding issue is that by using soft steel in contact zones and not using alignment pads on the outside of the bearings, any refurbishment job simply cannot produce a significantly improved product. All TRI can do in these cases is to return refurbished bearings in conditions that match the original bearings.

There is another very viable option

Retrofit TRI Align-A-Pad(TM) tilting pad journal bearings for GE Turbines and Generators make good products better. TRI can design and manufacture bearings with improved features:

  • 6-pad design with spherical dome on flat plate to provide the best contact demonstrated for rolling, tilting, and twisting to suppress sub-synchronous rotor vibration.
  • Alloy steel pads and support pad support disks that resist wear.
  • Superior Babbitt that permits particulate matter to embed, and still has the yield strength at bearing metal temperatures approaching 230 deg F on a continuous basis to function without Babbitt degradation.
  • Pads that are easy to maintain (rebabbitt, machine to specs, and to install in the housing).
  • Floating seal rings made from alloy steel with Babbitt lining that are used at both ends of the bearing housing to minimize oil flow exiting along the shaft.
  • Typical TRI Align-A-Pad™ bearings have heat treated alloy steel "saddle blocks" for "vector" alignment adjustments using both radial and tangential shim packs.

TRI Align-A-Pad™ bearings perform for 100,000 hrs between turbine inspections and overhaul

In Summary

Regarding GE Hydrogen seal assemblies, TRI is in an excellent position to modify, upgrade, or refurbish, these seals up to or in excess of 30-inch journals. TRI will refurbish existing seal assemblies or upgrade them as desired.

Regarding Tilting Pad Journal Bearings for the "classic" or more recent tilting pad journal bearings now in GE Gas Turbines, or D-11 Steam Turbines, TRI has demonstrated the skills to handle the wide range of de-signs that GE now uses.

While not discussed in this document, TRI has the engineering and shop skills to refurbish, modify, or up-grade any fixed bore bearing in any turbine or generator built by GE or other manufacturer.

Gear Box Upgrades

TRI Upgraded Gearboxes for Power Trains: Gas Turbines, Exciters and Other Applications

Gear Box Solutions:

  • Upgrade Bearings
  • Re-bore
  • Balance
  • Improved Oil Flow
  • Improved Sealing
  • New Instrumentation


  • TRI Upgrades complete gearboxes and provides upgraded bearings and other components for many gearbox applications

Upgrade your gearbox

Call 610-363-8570

After several attempts to have these problems dealt with by gear companies that made some of the original gearboxes for GE, and other independent companies that focus on gear boxes, the customer came to TRI for a complete Engineering Analysis of the situation. We used TRI’s Proprietary Journal Bearing Simulation Computer Program to identify the principal factors involved and developed analytical solutions. Then, TRI Engineers designed and offered optional solutions.

The set of solutions that were used included:

  • inspection of the bearing bores and shaft centerlines relative to each other, and when not correct, the housing was re-bored to provide proper centerline distances.
  • upgraded TRI bearings with a substantial increase in load carrying capacity,
  • certain modifications to the gear shafts, then balanced in TRI’s balance facility,
  • housing modifications were made to improve lube oil flow to the bearings,
  • housing modifications were implemented to control oil leaks through the horizontal joints due to high velocity oil thrown from the gears toward the internal housing surfaces, 
  • improved shaft seals, and 
  • bearing metal thermocouples located close to the load zones of the bearings
  • using oil leak resistant thermocouple fittings. 

This multi-point solution was implemented on a spare gearbox and then sequentially on the succeeding gearbox as each GT / gearbox / gen sets came up for a maintenance outage.




In some cases, the gears were rebuilt with new shafts, keeping the old gears. In some cases, TRI created gear drawings and then purchased a matched pair of new gears to the original gear specs. These gears were made by a well-known American manufacturer of “open gearing” using the current gear grinding capabilities. For all of the gearboxes, TRI made upgraded Babbitted bearings with a number of features that (a) increased the load capacity sufficient to withstand the uprated high MW conditions, (b) suppressed sub-sync vibrations, and (c) provided satisfactory bearing metal temperatures.

Westinghouse Shaft Driven Exciter Gearbox:

This customer has a series of 3 or 4 relatively similar Westinghouse 3600 rpm Large Steam Turbine-Generators that were built in the 1970s. Each unit has an exciter package that includes a shaft driven quill shaft, speed reducing gear box, and an exciter operating around 895 rpm. There was one spare gearbox available. 

 For years, these double helix gearboxes experienced high vibration, both transverse and axial, as well as wear of bearings and gear teeth.


TRI Consulting Engineers were requested to participate in alignment of a replacement gearbox and then to disassemble, inspect in detail, make recommendations, and then to remanufssembly, the teeth on the gear and on the pinion were found to have different profiles and not to have the centerline to centerline distance of the bearing bores. The original gears were hobbed, and did not have a good contact pattern. The wear pattern showed that the gears had been shuttling axially from one end to the other, consistent with the measured high axial vibration pattern. The hub of the quill shaft did not have a mating surface that properly contacted the end of the generator shaft, so it was not possible for them to mate properly, introducing a bowed rotor condition. 

TRI’s recommended solution, approved by the customer, included:         

  • a new gear set made by a well-known American Manufacturer of “open gearing” using current gear grinding methods
  • the remainder of the shaft profiles matched the original shaft profiles, 
  • new TRI Babbitted journal bearings with proper clearances,
  • the thrust bearing surfaces were shaped to provide enhanced load carrying ability and oil flow control,
  • the quill shaft was machined to provide an improved mating surface on the hub, and improved surfaces for measuring alignment during assembly, and
  • thermocouples were installed from the outside with leak-resistant fittings to measure the bearing metal temperatures in the load zones

TRI Manufactured Products and Consulting Services for Trains that Include Gearboxes, Fluid Drives with Internal Gear Sets, and Related Equipment:

TRI has these engineering, design, and manufacturing capabilities for manufacturing, upgrading, and remanufacturing a range of high powered gearboxes: 

  • Bearings to increase load carrying capability, and to suppress sub-synchronous rotor vibration (oil whip, oil whirl, and the like). TRI manufactures both solid bore bearings (circular bore, elliptical bore, pressure dam) as well as TRI Align-A-Pad ® Tilting pad bearings, as is most suitable for the application.
  • Remanufacture / repair gear box housings as necessary.
  • Build complete gearbox housings to suit specific applications. This need may arise to replace a damaged gearbox, or to make a “one-off” gear box assembly for a custom application.
  • Add instrumentation as desired: proximity probes, seismic probes, and thermocouples / RTDs.

TRI Rotor-dynamic and Journal Bearing Computer Simulation Programs and Services:

TRI has a repertoire of rotor-dynamic simulation computer programs that were created by TRI personnel, are very mature, and have been eminently successful: They have been used by TRI since the 1970s to provide evaluations of a considerable amount of gas compression equipment in many oil and gas fields around the world, as well as for the heavy rotating equipment in electrical generating plants across the US. These computer programs can be used to perform complete rotor-dynamic analyses of all types of equipment including gearboxes and related power trains from very small to very large:

  • journal bearing design analyses, almost all designs,
  • lateral critical speeds and lateral synchronous vibratory responses to unbalance,
  • lateral non-synchronous rotor stability analyses of multi-bearing trains, and
  • torsional analyses of power trains. 

TRI also provides field service with consulting engineers and field service technical personnel in order to evaluate problems, offer recommendations for improvements, upgrades, and/or repairs, and to install and align  equipment trains.

Special TRI Gearbox for Operating a Disconnect Coupling as Part of a Synchronous Condenser Start-up Package:

TRI has converted two 100 MW Turbine-Generators to Synchronous Condensers for a major utility in America. The design of the equipment train was based on US Patent 5,610,500 that was granted to TRI. Each startup train consisted of a large induction motor, a variable speed fluid drive, a speed increasing gear-box, a disconnect coupling, and an extension shaft connected to the generator shaft coupling. Thrust and journal bearings supported the extension shaft.

The gear box had unique features permitting the high speed pinion to slide axially under hydraulic pressure when it was rotating or not rotating. When it was not rotating, the disconnect coupling could be engaged hydraulically to the Extension Shaft, and when it was rotating, it could be disengaged hydraulically from the Extension Shaft.

TRI designed and manufactured this unique gear box, though, again, TRI purchased the ground gear set as “open gearing” from a major US gear manufacturer and TRI made the rest of the arrangement, including all of the hydraulic features involved. A full complement of temperature and vibration sensors was installed. This train of equipment, including the gear box, performed very well.

Variable speed fluid drives such as the Gýrol®* fluid drive have been used since the 1930s in the US to provide variable speed power to drive boiler feed pumps and fans. New fluid drives of a similar design are still manufactured today by TRI because they are very reliable and very efficient. TRI manufactures fluid drives for speed ranges from 600 rpm to over 5000 rpm and for powers from 3000 hp to 40,000 hp.

If your fluid drive requires maintenance in operational cycles less than 10 to 12 years, ask TRI to inspect your situation and make recommendations to improve the design/parts/operations. TRI designs and manufactures fluid drives that typically operate with 12-year inspection and refurb cycles without a need for opening between scheduled inspection and refurb outages. To achieve 100,000 hour runs, TRI offers upgrades for critical parts.

Common Upgrades

  • Journal Bearings
  • Thrust Bearings
  • Shafts
  • Shaft Seals
  • Impeller and Runners
  • Scoop Tubes
  • Scoop Tube Actuators
  • Couplings

Analysis and Resolution

  • Vibration analysis
  • Heat transfer analysis
  • Lubrication upgrades
  • Improved instrumentation
  • Eliminating design flaws

TRI supports over half of the American Standard Fluid Drives (13,000 hp to 30,000 hp) used for BFP Service. 

Extensive Service and Manufacturing Capabilities in 23,000 sq ft Facility - near Philadelphia, PA


*  Gýrol® is a registered trademark of Howden North America Inc.

Cracked Bearing Castings

3 Case Studies

TRI Explains the Cause & Provides Solutions

Cracks Found in Westinghouse Cast Steel Bearings with Conclusions and Recommendations for Resolution

Case 1

The first time that the subject of cracking of cast Westinghouse bearings came to the attention of TRI was in 1996. A 16" diameter generator bearing was found to have cracks in an axial face, Photo 1. There is nothing that can be done to repair cracks in such a bearing operating in this environment because there is no certainty of permanence.

TRI manufactured a replacement bearing using a forged steel ring made of AISI 1030 steel. The customer specified that the bore geometry be an exact duplicate the original circular bore including the overshot oil spreader groove in the axial center of the upper half. TRI manufactured this bearing as specified, Photos 2 and 3. The Babbitt thickness that TRI uses is a thin layer, approximately 0.100 " per side.

Case 2

 A utility indicated that cracks had been found in certain faces of large generator bearings of a Westinghouse unit in a nuclear power plant.

Case 3

TRI received an inquiry to replace a series of Westinghouse bearings with new bearings to accompany new retrofit turbine rotors in another nuclear power plant.

TRI proposed new bearings that would have a series of improvements including using forged low carbon steel instead of cast steel due to improved material qualities, thereby eliminating the possibility of cracking such as has been experienced in the industry with cast iron and cast steel bearings. One of these bearings is shown in Photo 4 mounted in the supporting yoke.


Causes of Such Cracks in Journal Bearings

While there may be differences between the precise causes of the various cracked bearings, those already found and those to be found, the reasons include the following:

Stress Risers: Porosity and Inclusions in Castings; Sharp Corners in Surface Profiles

Cast steel such as used for the Westinghouse bearings is a porous structure and usually has a significant amount of  inclusions (non- metallic material). The problem with porosity and inclusions is that they act as internal stress risers that can lead to cracks when static loads, vibrations, and thermal gradients occur.  Sharp corners in the profile of the surface also act as stress risers and have led to cracks.



Cyclic Stress Issues

There are both high cycle fatigue and low cycle fatigue issues at work in bearings:

High Amplitude Cyclic Stresses, Generally Related to Vibration:

High cycle fatigue usually relates to stresses due to vibration. For a 3600 rpm (60 Hz) machine, there are 5 million (5.184 x 10^6) rotations of each shaft per day, and each rotation causes an alternating stress cycle in the shafts as well as in the bearings and supporting structures. In other words, for a 60 Hz turbine-generator, there are 5.184 x 10^6 stress cycles per day for the shafts and bearing structures. For 8000 hours per year, there are 1.73 x 10^9 cycles per year, or 1.73 x 10^10 cycles per decade, or for forty years since installation, almost 6.91 x 10^10 cycles. For an 1800 rpm (30 Hz) machine in forty years, the number of stress cycles is half this amount, or 3.46 x 10^10 cycles.




While the general conception taught in engineering school is that carbon steel reaches an "endurance limit" such that the yield stress remains constant for an indefinite number of cycles, experience has shown that is simply not true, particularly if there are inclusions or localized stress risers (sharp corners) in the structure. A typical endurance plot in a text book stops at around 10^6 or 10^7 cycles, which is small compared to the number of cycles that these machines have experienced. Typically, endurance stress curves are created by averaging higher and lower failure stresses, and consequently, such endurance stress limits can only be used as a rough guide. The porosity and inclusions of cast steel act as stress risers, and the effect that they have on the actual endurance stress capability of a bearing varies substantially from bearing to bearing because the porosity and inclusions vary from bearing to bearing. This substantially reduces the predictability of finding cracks and/or the degree to which a crack will propagate into a bearing.

Photo 3


The static load of a rotor is exerted by a journal on an oil film and then in turn by the oil film on the mating Babbitt surface of the bearing. When the bearing is loaded downward near the bottom center, the bearing deforms into an ellipse, with the long axis in the vertical direction and the short axis in the horizontal direction for almost any method of support. This elliptical shape occurs both when the bearing is supported with full contact of a spherical surface on the lower half, Photo 1, or when the bearing is supported by two supports, one at each side at 45 degrees from the bottom, or when the bearing is supported by a yoke. Photo 5 demonstrates the elliptical shape of the elastic deformation of a yoke under load without the bearing installed. When a bearing is installed in the yoke, the bearing will have  the same elliptically shaped deformation as the yoke experiences.

In operation, during each cycle of rotation, the journal lifts and falls, and the bearing experiences cyclic oil film pressures that act on the Babbitt surface of the bearing lower half, adding to the static film pressures. These alternating film pressures (psi) contribute to the compressive stresses on the Babbitt surface and modify the stress distribution throughout the bearing. The alternating film pressures induce alternating stresses (psi), which may cause local stresses in the bearing steel backing to go cyclically from zero to tension, or to go from zero to compression, or to go from compression to tension, depending upon location in the bearing.


The stress distribution in an elliptical shape tends to be compressive on the inside of the bottom and top halves, and to be in tension on the outside of the bottom and top halves. Near the horizontal joints on each side, the pattern reverses. In operation, during each cycle of rotation, the journal lifts and falls, and the bearing experiences cyclic oil film pressures that act on the Babbitt surface of the bearing lower half, adding to the static film pressures. These alternating film pressures (psi) contribute to the compressive stresses on the Babbitt surface and modify the stress distribution throughout the bearing. The alternating film pressures induce alternating stresses (psi), which may cause local stresses in the bearing steel backing to go cyclically from zero to tension, or to go from zero to compression, or to go from compression to tension, depending upon location in the bearing.


The method of support influences the amplitude of the stress cycle. In generators, many bearings are supported by a continuous support of spherical shape along the bottom half, the best means of support. Many Westinghouse Turbine bearings are supported by two alignment pads on the lower half, each one 45 degrees from the vertical centerline. In this arrangement, the bearing acts as a bridge between the two supports, and the bridging effect accentuates the deformation of the elliptical  shape, increasing the peak amplitude of the combined static and cyclic stresses.

Cyclic Stresses due to Impacts Between Bearing and Bearing Pedestal:

Westinghouse bearings typically are installed with clearance between the top bearing alignment pad and the bore of the housing. This permits the bearings to bounce on the alignment pads during higher amplitude rotor vibrations, such as may occur when going through a critical speed, and this bouncing acts as an impact with localized stresses that are extremely high. It only takes a few events, or perhaps only one such event, to create a sufficiently high localized stress to induce an incipient crack in a casting. Such a crack may be so tight and so small that it may not be able to be recognized by MPI techniques. It may be only a few thousandths of an inch long and it likely will not cause an immediate failure.  However, once started, the crack acts as a very high stress riser, and cracking may propagate to form a fully developed crack.



Low Cycle Stress Conditions, Generally Related to Thermal Conditions:

- During Normal Operation:

Consider a freely supported steel bar 16 inches long that changes temperature by 10 degrees. It will change length by 0.001 inches.

Now consider a large steel bearing with dimensions in excess of 16 inches. During normal operation, every bearing is hotter in the axial center and near the bore than on any external surface. The internal portion of the bearing may approach 180 to 190 degrees F, while the external surfaces may be as low as 110 degrees, the normal oil supply temperature. As a result, this bearing may have temperature gradients of perhaps 60 degrees over 10 to 20 inches. Because the internal or hotter sections of the bearing expand in size, and the external or cooler portions do not expand by the same amount, such thermal gradients induce substantial tensile and compressive stresses in the part. Generally, the outer or cooler surfaces are in tension and the internal or heated sections are in compression. Please note that during a cold start, it is possible for a bearing to be 180 or 190 on the inside and less than 110 degrees on the outside, causing higher stresses. The result is that large bearings endure low cycle fatigue conditions from the thermal cycles that occur every time a turbine-generator is started and stopped.

- Quenching During Babbitt Centrifugal Casting:

Another form of low cycle fatigue occurs during centrifugal Babbitt casting. Each bearing is heated to approximately 425 degrees F, and while spinning, liquid Babbitt at 800 degrees F flows in, contacts the steel backing, and spins up to the rotational speed of the steel shell. Then the steel shell is quenched on the outside with water, usually cold water between 70 to 120 deg F. Within 10 to 40 minutes or so, depending upon bearing size, the bearing has returned to room temperature. During this water quenching process, the external surfaces are cooled first, putting them into a substantial tensile stress condition, while the inner / hotter sections are in compression. This quenching activity has been known to crack cast iron bearing shells during the quenching process.

- Oil, Water, and Hydrogen in the Pore Structure of a Casting:

During operation, the pores in cast bearings fill with oil and water, and permit hydrogen to be absorbed easily. Prior to any Babbitt casting process, all bearing shells, and particularly cast steel bearings, are supposed to be heated slowly and for many hours to drive off any absorbed liquids and hydrogen gas. When a bearing is heated, these absorbed liquids and gases expand in the pores, and generate internal pressures that tend to cause tensile stresses in the structure of the cast material. Such tensile stresses can be a contributing factor to initiating cracks.

Conclusions and Recommendations:

The combination of static stresses, alternating cyclic stresses, and thermally induced stresses leads to tensile stresses that are of substantial magnitude in certain surfaces of bearings. Cast bearings have inclusions and porosity which act as stress risers. Larger bearings carry heavier loads than smaller bearings, and therefore, are likely to have higher amplitude stresses, both static and alternating.

On the other hand, the yield stresses and endurance stress levels of large cast bearings are a function of material only, not size. They do not increase with bearing size.

A conclusion is that because the stress levels increase in large bearings relative to the yield and endurance limits, it follows that larger bearings made of cast steel are likely to be more susceptible to experience cracking than are smaller cast steel bearings.

It is known that due to rotor vibration issues, many cast steel fixed bore bearings in 3600 rpm (60 Hz) Westinghouse HP, IP, and LP turbines as well as generators have been removed and replaced with tilting-pad bearings. These tilting-pad bearings are made with materials other than cast steel, and so these bearings are no longer in the population of cast steel bearings that are in service in Westinghouse LST-Gs.

The bearings that are least likely to be changed to another bearing type in order to solve a rotor vibration issue are those bearings that support heavier rotors and those bearings that are part of 1800 rpm (30 Hz) machines.

A conclusion is that cast steel bearings that are most likely to experience cracking as discussed above include those that were installed in nuclear powered Turbine-Generators that were built in the 1960/1980 era.

A conclusion is that bearings that are made from forged or hot-worked steel are not likely to experience cracking.

This recommendation addresses bearings made of cast iron or cast steel that are in Westinghouse Large Steam Turbine-Generators. If these cast bearings have not been inspected recently, each of them should be inspected when any of the following events occur:

  • During the next major outage, each bearing should be removed and inspected.
  • If there is an unexplained change in the DC gap voltage, vibration pattern, or operating temperature, the affected bearing should be inspected.
  • During any subsequent outage when the bearing is exposed or removed, at least each face should be inspected

Even though the odds of a bearing cracking to failure are small, the greatest justification for inspection is that the consequences of such a bearing failure could very well be catastrophic (interpretation: severe damage to the entire machine, including the possibility of breaking up at speed). The nuclear industry appears to be getting a new lease on life, and it is critical that failures of any type be minimized to near zero, particularly an event such as damage due to a cracked bearing when the crack can be avoided easily by NDE means: visual, MPI or dye penetrant. Exotic methods and extensive training are not required to find these cracks.

TRI recommends that it is appropriate to change out every bearing in a Westinghouse Large Steam Turbine-Generator that is now a cast iron or cast steel bearing, and replace each one with a bearing made from forged or hot worked steel backing and thin Babbitt linings.

TRI recommends that an improvement can be made by installing another support point (an alignment pad) in the bottom center of the bearing to reduce the bridging effect.1

TRI recommends that if a crack is found in a bearing, the bearing must be replaced. Do not consider a weld repair; there is no certainty of permanence.

TRI recommends that bearings for all Turbines and Generators should be made using forged or hot worked carbon steel and not cast steel, for the following very good reasons: 

Forged or hot worked steel has these improved properties:

  • Higher yield and tensile strengths, higher endurance stress levels, greater ductility, and not brittle,
  • No significant porosity and very few inclusions are present to act as local stress risers,
  • No need for dovetails (mechanical Babbitt anchors) because tinning compounds today permit excellent bonding between Babbitt to forged steel backing,
  • Easier to tin and Babbitt,
  • Less likely for the Babbitt-steel bond to break and Babbitt to peel away, and
  • High pressure lift oil can be fed directly through drilled holes in the steel because the forged steel can withstand the pressures involved, whereas cast steel requires steel pipes to be installed through holes in the cast steel because high pressure oil can crack the casting and/or oil can pass through the porosity of a casting, thereby reducing the effectiveness of the lift oil system.

As a summary, TRI's Consulting Engineers have been solving rotor vibration and bearing damage issues since 1961, representing almost fifty years of dedicated service to the rotating machinery and power generation industries. TRI has been designing journal bearings of all types to solve these issues for all of this time, and have been manufacturing bearings since 1973. In recent years, TRI designed and built a large centrifugal Babbitt casting machine, Photo 6, for bearings up to 70 inch OD and 20,000 lbs, which covers every bearing in any Large Steam Turbine-Generator that we know of. 

The discussions herein and the photos provided clearly demonstrate that TRI understands the issues and has the capability to design and manufacture any size bearing for any Westinghouse LST-G.

Consequently, TRI requests that you please consider having TRI Engineers evaluate any rotor vibration and/or bearing issue that you have, and if replacement bearings are appropriate, TRI suggests that you request TRI to manufacture suitable. 

Printer Friendly Version of this Tech Note

Dr. Mel asks, "Why don't you fix it"?

The typical answers are: 

Because we had a spare bearing of the same design, so we shut the Turbine (or other piece of equipment) down, installed the spare over the weekend, and restarted.  However, after time, the bearing failed again.

Because we had a different mechanical contractor repeat the installation with a spare bearing of the same design.  But again after time, that bearing failed the same way.  Maybe it’s not the contractor, and maybe it’s not even a maintenance issue. Instead it might be an issue with the OEM equipment design as used currently.

Because a seemingly perpetual warranty arrangement exists with the OEM, and the OEM provides spares when we need them.  Consequently, we are in a quandary because we lose production income and we cannot go out to get a specialist who could solve the problem.   

Because a competing OEM claims that a complete replacement of our expensive equipment is the answer.

Because if the OEM can't solve the problem, we doubt anyone else could solve the problem.  

Because we use a competitive bidding process.  A local shop with the lowest cost always gets the award.  While we are not happy with the results, we have no choice but to get a cheap refurbishment of the original (failed) bearing and to use it until it fails again.

Because our standard solution tree has not yielded a long term solution. Our committee meetings use a solution tree with many branches.  Unfortunately, our attempts to fix the problem have not worked.

If any or all of these reasons seem familiar, you might try another route.

Call TRI. TRI is a very experienced and capable engineering and manufacturing company.  TRI performs detailed evaluations of the design of the rotor-bearing system with the objective of permanently solving the problem. Typically, TRI's solution process results in an identification and explanation of the problem and the solution, described in plain language and sketches for all to understand.  With the customer's approval of the solution, TRI will complete a specific design of upgraded bearings or other hardware to resolve the problem for consideration by the customer.  With approval, TRI will then manufacture the products in TRI's highly capable shops.  TRI will subsequently provide direction for installation and will monitor start-up.

For decades, TRI has been solving design problems for all types of rotating machinery - Steam Turbine-Generators from 5 to 1350 MW, pumps- horizontal and vertical, compressors, motors, variable speed fluid drives, gear boxes, and more. In most cases, for a range of reasons, OEMs or others would not or could not solve the issues at hand.  TRI fixes rotating machinery with long-term solutions.

TRI's primary methodology is to use TRI's proprietary simulation modeling computer programs and other commercial modeling computer programs to evaluate the bearings and rotors to create the basic design features of the solution.  Then TRI uses CAD to complete the design for TRI's shops to manufacture.  

Today, TRI has upgraded journal bearings installed and operating in over 55,000 MW of power generation in America and internationally.  In summary, TRI has developed numerous upgraded designs of journal bearings, lube oil systems, and a variety of new equipment such as high-powered variable speed fluid drives for pumps and fans.  

Incidentally, in recognition of TRI's innovative abilities to solve a wide range of rotating machinery problems with new solutions, TRI has received over 20 US and European patents, the latest being U.S. Patent No. 9,841,055 for Vertical Guide Bearing Improvements. 

TRI is supporting spring 2018 outages and preparing for fall 2018 and spring 2019 outages.  Please call TRI if we may support your outage with refurbished or new components.


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Improved Competitiveness for Conventional Coal & Gas-fired Power Plants

A Justification for Re-evaluating Maintenance and Upgrade Policies.

For Many 1960-1970 Vintage Plants, Efficiencies can be Improved up to 15% (or more) and Operating Ranges can be Widened.

With the new administration in Washington, we have already seen a difference in the regulatory philosophy being exhibited. A new attitude has appeared which strives to greatly reduce regulations on electricity generators and at the same time protect the environment in a more reasonable manner.

Under the prior regulatory regime, the regulations were so onerous that many conventional coal-fired and gas-fired generating stations were either (a) planned for permanent shut-down because the regulations were making them unprofitable, (b) the regulations would force installation of very expensive emission controls, or (c) the stations would run with minimal maintenance until they were no longer operable, and then close. 

With the new attitude in Washington, this is an opportune time to re-evaluate all maintenance and upgrade improve efficiency, performance, availability and reliability.

Many Generation Stations are Excellent Candidates for Upgrades with Substantial Efficiency Improvements:

Candidate Plants: Prior to the 1990s, utilities enjoyed a constantly growing demand for electricity. Most generating stations of the era were designed as base-load power generators operating at or near max generation. Equipment was selected for quick delivery and not necessarily sized to optimize the efficiency of the generating unit. With the range of options available today, efficiency and performance optimizations for these older plants can be achieved.    

Today the question before us is this: Are these older plants valuable or are we better off just shutting them down? Consider this: As each new solar or wind project comes on line, the need for stand-by power increases. The renewable source generators provide intermittent power. Stand-by generating stations are required in periods of reduced solar and wind generation. Due to the need to have back-up power plants and to pay for the capital to build new plants, the levelized cost of solar and wind is very high—3-5 times the cost of electricity from existing coal fired powered plants. However, these older plants have been PAID FOR. Only the upgrades have to be paid for, making these plants highly desirable.

Existing generating stations that can turn down to low generation and then can come up to full power in a short period of time can help to alleviate the problems caused by intermittent sources. Due to the nature of the steam cycle, sub-critical steam plants that are retrofitted with known upgrade technologies are better suited to run down to 10% of maximum capacity. Such plants can provide this much-needed stand-by capacity, and with lower heat rates, they can compete with other generating stations.

Effective Upgrades to Achieve Substantial Efficiency, Availability, Reliability, and Operability Improvements of Rotating Machinery:

The major technologies that can be implemented for the turbine-generators and the associated auxiliary rotating equipment that can significantly improve the efficiency, availability, reliability and operability of power plants are these:

  1. Retrofitting 3-D steam path technology can often improve efficiency by 6-10%.
  2. Optimizing the size of high power Boiler Feed Pumps, Induced Draft Fans and Forced Draft Fans, as well as introducing Variable Speed Fluid Drives where possible can improve the efficiency from 2% to 4% for each function.

For conventional coal-fired and natural gas-fired large steam turbine-generator units, a good starting point is this:

  1. Select expected operational functionality, depending in part on boiler design:
    • To operate on constant throttle pressure over the entire load range, using partial arc control valve methodology, or
    • To operate on "Sliding Pressure" over all or a portion of the load range.
    • Determine desired minimum stable generation as a percentage of full load rating.
  2. Implement an upgraded steam path using available 3-D steam flow design techniques and control valve operation to achieve the operation method selected above. HP, IP, and LP turbine sections are all candidates for upgrades by the major turbine manufacturers. TRI Align-A-Pad® tilting pad bearings have been designed to suit the particular characteristics of upgraded turbine and nozzle block designs, permitting even greater improvements in MW generation and efficiency than can be achieved with standard OEM bearings. With the resulting redesigned new rotor and bearing system, greater availability, reliability, and operability can be expected. Improved reliability leads to fewer starts and stops and reduces associated costs.
  3. Optimize sizing and powering of large auxiliary equipment, primarily boiler feed pumps and fans:

Most BFPs and Fans are NOT optimized to support the existing turbine steam path, and more importantly at this time, they are NOT optimized for any upgraded turbine steam path. Furthermore, it is very UNLIKELY that they are designed for operating over a wide operating generation range including stable operation at a new minimum of approximately 10% of maximum generation. Such low generation conditions that are stable can be and have been achieved using Variable Speed Fluid Drives to power BFPs and Fans.

Regarding BFPs, the impellers and stationary parts can be redesigned and manufactured to optimize stable feed water flow conditions and power consumption for the revised turbine operating conditions.

It is advantageous to drive the BFPs by Variable Speed Fluid Drives (VSFDs) that are in turn driven by either an induction motor or the end of the turbine-generator shaft. TRI designs these VSFDs and the associated auxiliary equipment to be able to operate anywhere in the head-capacity chart for the BFP that suits the turbine. It is interesting to note that a BFP driven from a VSFD powered by the main turbine shaft is an extremely efficient method for powering boiler feed pumps, as compared to mechanical drive steam turbines because the steam stays in the main turbine which has much higher efficiency.

Regarding fans, fixed geometry fans, especially centrifugal fans, are simple devices and require relatively low maintenance as is necessary to achieve maximum availability and reliability. Fans can be designed or modified to suit the optimum air flow needs. The air flow controls can be modified to be primarily speed controlled and depend less on either outlet damper or inlet vane control. This is a critical point for improved efficiency over the entire load range, especially when low power for overnight operation is required.

Variable Speed Fluid Drives can be sized and manufactured to match the optimized fans, regarding fan speed range and absorbed power.

Electric Motors of sufficient power are used to drive the Variable Speed Fluid Drives. An advantage to the use of VSFDs is that the motors have only the input sections of the attached VSFDs to drive, and therefore, a 6000 hp, 600 rpm motor can rapidly accelerate to reach design speed in only a few seconds, perhaps 3 to 5 seconds. Much shorter than 45 to 60 seconds required to start when the motor is directly coupled to a heavy ID fan. This definitely minimizes the period of high inrush current, and therefore, minimizes the duty experienced by the motors. After reaching full speed, the VSFD is loaded.

Calculations for New Operating Conditions:

To determine the overall system efficiency improvements obtained by using the upgraded components described above, a computer program such as PEPSE can be used. PEPSE is a steady-state energy balance software program that calculates the performance of electric generating plants. It is supported by Curtiss-Wright.

While the efficiency improvements are dependent upon the circumstances for each generating unit, the clear consequence is that very substantial efficiency improvements can be made when all of the individual contributions are added up. This applies throughout the entire generation range as will be needed in the future, not just the maximum generation point typically used as the only evaluation point in the past.

TRI's History over the past 50 Years:

TRI has been in the business of solving rotor vibration, bearing damage issues, and other rotating machinery matters for over fifty years. This includes engineering analysis, design, manufacturing and installation of many retrofits and upgrades to improve operability and efficiency of power plants.

Dr. Mel with a large fixed bore bearingIn this Evaluation Process, Please Consider What TRI can do for your Equipment:

  • Babbitted Bearings: Fixed bore and tilting pad
  • Basic replacement and repair.  Most repairs are completed in a few days.   Simple upgrades using a different bearing bore geometry are completed in the same time period as machining the original bore geometry.  Our time schedule and pricing beats most OEMs.  TRI bearings have proven to be the best for reliability and for resolving "problem" bearings.   New fixed bore replacement bearings are manufactured in 4 to 6 weeks after receiving the steel forgings.
  • New sophisticated tilting-pad bearing upgrades (TRI Align-A-Pad®) control difficult rotor vibration and bearing damage issues. TRI can provide the engineering analysis of the equipment problems and can make these bearings in 4 to 8 weeks after receiving the specified steel.
  • A very common use of TRI Align-A-Pad® Bearings is in HP or HP-IP Steam Turbines of all sizes. These bearings are capable of controlling rotor vibrations due to unbalance over the entire load range for partial-arc operation, or to eliminate sub-synchronous rotor vibrations, including eliminating "steam whirl" when the bearings are lightly loaded.
  • "Lift oil" (jacking oil) mods to existing (or new) bearings reduce bearing wear, thereby reducing maintenance, and/or reducing turning gear motor amps.

Vibration Analysis and Diagnostics:

Today, there are many power plants and other companies that perform analyses and diagnostics of rotor vibration data taken from rotating machinery. TRI has been performing this service since 1971. This activity provides information that can be helpful in selecting what bearing designs would improve the vibration control or reduce bearing damage. Historically, based on this type of diagnostic activity, TRI expanded into the more complex business of making and installing bearings to resolve the identified problems. TRI continues to offer vibration analysis and diagnostic services today, as desired by power plant personnel.

Variable Speed Fluid Drives (Hydraulic Couplings) for Boiler Feed Pumps:Size 270 Single Circuit Fluid Drive for a boiler feed pump

  • Large Boiler Feed Pumps are driven by Variable Speed Fluid Drives, Variable Speed Steam Turbines, or by Variable Frequency Electrical/Electronic Motors.
  • The most robust and reliable method, as well as the lowest cost alternative particularly when long term maintenance is considered, is the use of large variable speed fluid drives driven by the main steam turbine-generators or by induction motors. Many years ago, TRI developed upgraded designs for a major group of these Fluid Drives, that when incorporated, typically permit 10 to 12 years of operation between inspections.

Variable Speed (Mechanical Drive) steam turbines typically require maintenance on the valves and turbine steam path every 2 to 6 years, which affects availability and reliability and increases maintenance costs.

Motors using variable frequency electronic drives are built on solid state electronics. As such, they can suffer an instantaneous shutdown from loss of a solid-state component, and they tend to become obsolete in a few years.

For Variable Speed Fluid Drives, TRI provides these products and services:

  • Remanufacture rotating elements to TRI standards.
  • Remanufacture Complete Fluid Drives to TRI standards.
  • Manufacture new spare parts.
  • Field Service for inspection, repair, and refurbishment.
  • Manufacture complete new Fluid Drives for almost any application up to 40,000 hp.

Lube Oil and Lift Oil Systems:

  • TRI designs and manufactures lube oil systems in a full-size range for normal operation.
  • For emergency lube oil supply, TRI offers and has developed a system that is an AC-DC hybrid. The motor, switchgear and Variable Frequency Drive are all standard AC. A conventional UPS package contains adequate batteries to supply the DC power required by the UPS inverter to provide AC power for the specified period of time. This eliminates all DC power apparatus, other than the internals of the UPS.
  • TRI designs and manufactures Lift Oil Pumping systems for turbine and generator bearings.

Lift oil skid for heavy rotors

Hydrogen Seals for GE Style Generators:

Most GE style generators in service today still use Hydrogen seal rings that are made of Bronze and are segmented into 4 quadrants. While these are reasonably effective, many have higher hydrogen gas loss than desired, sometimes due to vibration that displaces the seal quadrants. These original seal rings are somewhat difficult to assemble, to install, and to maintain. A very skilled technician is required, one who has considerable experience and attention to detail.

TRI Hydrogen Seals for GE GeneratorsTRI manufactures a newer version of these Hydrogen seals that use steel rings with Babbitted bores. Each ring is split into two parts which are bolted and doweled at the joints permitting a rounder and flatter seal ring and a more effective shaft seal. The clearances between the journal and these steel seal rings when set cold are intentionally larger than those for bronze seal rings when cold due to the difference in thermal expansion coefficients. Note that at operating temperature, the design clearances for the bronze and steel rings are intentionally identical.

With improved shaft seals, there is less gas leakage, so higher gas pressures can be used providing improved cooling. The operating results are that higher MW and MVars can be obtained with less overall generator maintenance.

A critically important feature of the TRI hydrogen seal design is that the housing has a removable outer top half that permits much easier installation, removal, and maintenance of the seal rings and associated garter springs.

The TRI Hydrogen Seal housing and ring assemblies replace existing Hydrogen seal assemblies - as complete assemblies. The TRI Hydrogen Seal housings at both ends of the generator are insulated from the frame.


For help with upgrades, modifications, or simple repairs that you are pursuing today, please let us work with you to optimize the solutions to your equipment issues. With the administration change and a new attitude in Washington, let’s start making the upgrades.


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Technical Notes from Dr. Mel Giberson, P.E. - TRI President March 30, 1998

 Significantly Increase Power Efficiency

Variable speed transmissions offer substantial power savings over constant speed and compressors with flow control devices.

Examine the chart to the right. The difference between the power consumption curves represents the power saved using a TRI fluid drive transmission. Additional savings are possible as a result of needing a smaller driving motor.

Fluid Drives 
   versus Solid State VFDs

Once the decision to control flow by variable speed has been made, one more question remains. Should the speed be controlled by a fluid drive or a solid state VFD? Maybe you are using a solid state VFD. If you are, then ask yourself these questions:

  • Does your VFD trip out during power fluctuations?
  • Does your VFD cog at low speed?
  • Does your VFD or motor overheat?
  • Do you require a specialized technician?
  • Do you have difficulty locating spare parts?
  • DO you want higher efficiency?

Are you using the most efficient means of process control?


TRI Builds Four new Fluid Drives Transmissions for natural gas handling platform. The TRI Model RAH fluid drives transmit power from gas turbines to generators. The turbines operate from 1900 rpm to 3000 rpm. The 4-pole synchronous generators are driven at a constant 1800 rpm and provide electrical power for other equipment on the platform

New Literature on the advantages of variable speed fluid drive transmissions is available. TRI offers two lines. Model RAH fluid drives operate from 50 to 4,000 hp and up to 3,600 rpm. Model FH fluid drives operate up to 40,000 hp and 15,000 rpm.

TRI designs and manufactures variable speed fluid drives transmissions

emphasizing small size, few parts, high reliability and low capital costs

 Tel: 610-363-8570 or 800-363-8571     Fax: 610-524-6326     EMail: This email address is being protected from spambots. You need JavaScript enabled to view it.

TRI Answers phone calls, returns e-mails and responds to fax inquiries


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Technical Notes from Dr. Mel Giberson, P.E. - TRI President 

August 18, 1998

 $7,000 Per Megawatt-Hour ($7.00 per kwh) !!

June 25,26, 1998

 Before deregulation, bulk electricity genearlly cost $12 -$55 per MWH (1.2¢ to 5.5¢ per kwh). The most inefficient gas turbine or diesel cost $100/MWH (10¢ per kwh). Those prices were considered "too high". "Become competitive" was the call! Deregulation pressures brought severe cuts; eliminating spare parts, people, plants, marginal equipment. Very little new capacity was added.

The intent of deregulation was to reduce the price of electrical power to the customer. June 1998 was a wake-up call. Electric power can be vary valuable on the "free market". In June the price peaked at over 100 times the regulated price, even though actual generation costs now are slight reduced. Electricity via utilities has been considered a necessity for all. Will it remain that way?

With these high prices to buy or sell power now a reality from time to time, it is important that Generating Stations first must be available and reliable, and second, generation costs should be as low as reasonably possible.

TRI can help Utilities meet these Objectives to increase availability, reliability,
and cost effectiveness, and to minimize construction of new generation facilities.
 Utility Objective
   TRI Products and Services
 Tilt pad & Ellip
Turb & Gen
Variable Speed
Fluid Drives
(Many Models) 
 - Reduce fuel consumed by 1% to 3% on average   × ×
 - Reduce CO2 and related greenhouse gases, to help meet objectives of Kyoto treaty    ×  ×
 - Operate on Sliding Pressure  ×  ×  ×

- Reduce Min./Increase Max. Generation Load × × ×
- Maintain minimum seal clearance in turbines  ×    
 - Minimize vibration over entire load range. ×    
- Operate longer between outages × × ×
- Control System Voltage and Power Factor × × ×
- Increase Max. Transmission & Distribution Load     ×

Contact TRI for more information about TRI's Products and Services, to schedule a visit or seminar in your plant

Upgraded Bearings: TRI Align-A-Pad Bearings® or Elliptical Bearings to 24" bore, that eliminate generation load restrictions.

Quality Spare Parts for Fluid Drives and Turbine or Generator Bearings

Variable Speed Fluid Drives (all new equipment) for Large Pumps, Fans, Compressors: to 40,000 hp or to 15,000 rpm.

Your Equipment Rebuilt Carefully and Completely

Synchronous Condensers, 30-1000 MVA, turnkey, includes starting equipment, for existing generators or new locations

Outage Maintenance Services

Please visit us at these Exhibitions this Fall:

ASME Int'l Joint Power Gen Conference & Exposition, Baltimore, MD Aug 24,25, 1998, Booth 310

27th Turbomachinery Symposium, Texas A&M, Brown Conv Ctr, Houston, TX Sept 22,23,24, Booth 360

Power  Generation International Conference, Orlando, FL December 9,10,11,1998, Booth 1425

Please help us update our database: If the addressee has moved, should be deleted, or others should be added, please advice. Thank you.

Tel: 610-363-8570 or 800-363-8571     Fax: 610-524-6326  


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Technical Notes from Dr. Mel Giberson, PH.D., P.E.  -  TRI President 

December 1, 1998

“It is cheaper to buy power than to make it” is being re-evaluated by electric utilities across the U.S.

Last summer showed that utilities purchased power at over 100 times normal generation costs.

TRI Resolution of Turbine High Amplitude Rotor Vibration Problem

Problem and Solution:

A utility has several identical 190 MW, 3600 RPM large steam turbine-generators with excellent heat rates and a vibration problem at certain loads (certain control valve positions). With the original bearings, it is not possible to balance the turbine rotors at all loads. The typical solution has been to operate the units at fixed loads near maximum generation. Because other units have to be turned down further or shut off at night, the resulting system costs are relatively higher. In 1995, TRI designed, built and installed a set of TRI Align-A-Pad® tilting pad bearings for the HP and IP turbines of one of these units. The rotorbearing dynamic characteristics were changed so that the turbines can now be balanced at all MW loads. The new system exhibits lower vibration and reduced turbine losses. The system is now run by the Automatic Generation Control (AGC) and the overall average generation cost for the system has been reduced.

As this electric utility re-evalulates power sourcing and costs, units are being retrofitted with TRI AlignA-Pad bearings. Contact TRI with a description of your turbinegenerator rotor vibration or bearing problems, and TRI will be pleased to provide you with a proposal for resolution. TRI offers performance warranties in most cases.


TRI Replacement of Older Fluid Drive Impellers and Runners Damaged by High Cycle Fatigue

Problem and Solution:

Most fluid drives installed in the U.S. were put into service in the 1960s. With increasing service life, fluid drive impellers/runners are beginning to fail via endurance limit problems. Also known as High Cycle Fatigue (HCF), an impeller/runner blade fails due to blade passing excitation frequencies that match the blade natural frequencies. The problem arises more when units are used in sliding pressure applications because the output shaft speed varies widely. Flaws in the material or other manufacturing defects can exacerbate HCF problems.

TRI has solved the HCF problem by manufacturing new impellers and runners using improved blade shapes, materials, and manufacturing techniques. With increasing probability of HCF failure of older units due to extended time in service, and because impellers and runners have long lead times, TRI recommends a spare rotating element or a complete spare fluid drive for critical service applications. If not possible, TRI recommends purchasing spare impellers and runners. Such spares permit a fluid drive assembly to be rebuilt quickly, minimizing the time that a utility is exposed to the prospect of purchased power at exorbitant rates.

For the most demanding applications, TRI manufactures impellers and runner with integral reinforcing rings, US patent 5,331,811.



  • Contact TRI for a review of your existing, proposed or conceptual fluid drive applications. 
  • Contact TRI for spare parts, repowering/upgrading, new fluid drives to improve efficiency of fans or BFPs. 
  • Contact TRI for replacement of electronic variable frequency drives with more reliable fluid drives.

Updated and expanded catalogs of TRI products and services are now available.

Please visit us at these Exhibitions:
Power Generation International Conference Orlando,  FL December   9, 10, 11, 1998
Energy Generation Conference Bismarck ND January 26, 27, 28, 1999
Electric Power ’99 Exhibition Baltimore, MD April 20, 21, 22, 1999


Please help us update our database: If the addressee has moved, should be deleted, or others should be added, please advise.  Thank you 


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September 1995                     

Technical Notes from Dr. Mel Giberson, P.E. - TRI President

MORE PATENTS for TRI: Advancement in Design & Manufacture of Impellers from Forgings.

Pat. 5,133,811: Fluid Drive Impellers and Runners are now made with Integral Reinforcing Rings.
This patent permits improved designs that are much stronger, more hydraulically efficient, and have higher vane passing frequency: Long, Long Life. As the older fluid drive impellers and runners develope cracks in the vanes, often attributable to either cyclic operation or sliding pressure service, the new TRI Impellers and Runners should be used, as they are designed to survive in the rough service applications.

Pat. 5,438,755: Shrouded MONOLITHIC Impellers such as Boiler Feedpump Impellers. The new TRI procedure permits impellers to be made from solid forgings. It is particularly applicable for larger impellers with passageways having long, curved arcs from the inlet to outlet. This new TRI process eliminates casting and/or welding, typical of conventional impellers.

Personnel Announcement: Mr. Richard S. Gregory has joined Turbo Research Inc. as Vice President - Marketing and Sales. Mr. Gregory brings many valuable talent and skills to TRI. He was Vice President and General Manager of Kingsbury, Inc. for many years. He obtained his Masters of Science degree in Mechanical Engineering from the university of Pennsylvania, where his studies included film bearing design. In addition to marketing and sales responsibilities, Rich coordinated many of TRI’s production functions. You will find Rich to be a valuable resource at your service. We are delighted to have Rich join TRI.

Plans for Outages: Reduce Vibration, Upgrade Bearings, Inspect Fluid Drives.

Does your equipment need Babbitted oil-film Bearings that will permit extended operating times between outages? TRI solves difficult bearing and vibration prblems with bearings that can tolerate more unbalance, higher temperatures, wider load ranges (unloaded to high load). TRI manufactures "State of the Art" Babbitted Film Bearings for Steam or Hydro turbines, Generators, Fluid Drives, Motors, Pumps, Gearboxes, Fans and Compressors. TRI Bearings include: self-aligning tilting pad journal bearings, elliptical/fixed bore journal bearings, load-equalizing thrust bearings.

Fluid Drives: Inspections, Upgrades, Repairs, New Parts, Oil Systems, Filters, Field Service, and New Applications.

TRI performs all functions for fluid drives: TRI rebuilds American Blower, American Standard, Voith fluid drives, with new TRI parts. TRI solves vibration problems that are related to load, speed, or scoop tube position. TRI replaces CUNO strainers with real duplex oil filters designed to fit. TRI manufactures New Fluid Drives to optimize variable speed applications to 40,000+hp. The lost heat can be fully recovered in many applications.

Please contact TRI to describe "PROBLEMS ON YOUR MAINTENANCE LIST" for which you WANT SOLUTIONS, or to request TRI Product and Service information:

  • TRI Consulting Engineering - to solve problems and design upgrades
  • Rotor-bearing performance analysis - by TRI proprietary computer simulation
  • Seminars on Bearings Designed and Fluid Drives
    •      designed: related to performance of power generation equipment
    •      drives: design, operation, maintenance
    •      content and dates arranged to suit needs of your power plant.
  • Arrange a visit of TRI’s new Product and Service Display Van

Please advise us of any changes, additions or deletions in FAX numbers or mailing addresses for you or your associates by calling (800) 363-8571. We thank you for you help in updating our data.

Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings


Phone: (610) 363-8570           TRI E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it. Fax: (610) 524-6326           TRI Web Site:


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August 1996                     

Technical Note from Dr. Mel Giberson, P.E. - TRI President

Reduced Reliability of the AC Power Grid
          The summer of 1996 has already seen three major power outages          


Although deregulating power has reduced generating costs, the recent major power outages in North America confirms that the power grid reliability has been compromised. In response, generating plants should be:

  1. Implementing measures to protect against damage during such an outage
  2. Re-engineering for faster restarts with less complications

Turbo Research, Inc. offers proven solutions for increasing the ability of power generation equipment to survive outages and stabilize distribution systems.

  • "State of the Art" Emergency Lube Oil Systems for all types of rotating machinery

  • Journal and thrust bearings that are more resistant to short term interruption of the lube oil supply

  • Motor driven boiler feed pumps with variable speed geared fluid drives

  • Synchronous condensers converted from existing generators (all sizes) with independent starting capability


          Don’t wait for problems          


Call TRI for information about consulting services and proven TRI manufactured components and systems.

TRI does answer phone calls and returns Fax Messages
Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings
Phone: (610) 363-8570           TRI E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it. Fax: (610) 524-6326           TRI Web Site:


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August 1997                    

Technical Note from Dr. Mel Giberson, P.E. - TRI President


Extension Shaft Vibration

Large turbine and generator rotors are frequently designed with large bearings and small extension shaft. Many extension shafts have high amplitude vibrations causing damage to the steady rest bearings.

TRI can answer questions and provide solutions. Using computer models, TRI analyzes bearing performance and vibration characteristics for turbine-generator-extension shafts


Bearings, Shafts & Pedestals
Contact TRI for a source with proven design and fabrication experience.

» Should the design incorporate steady rest bearings?
» How much "lift" is appropriate for a steady bearing?
» How much "lift" will cause fatigue and failure?
» How will the critical speed be affected?
» If required, what is the best type of coupling?


Variable Speed Drives

Look to fluid drive technology for increased reliability, efficiency and noise reduction.

Variable speed power above 400 HP is delivered most reliable with fluid drive technology. With TRI's latest advances, fluid drives can be designed more efficiently than either electronic variable frequency drives or mechanical drive steam turbines. By introducing a second element in a surprisingly simple package, the new TRI design has dramatically increased efficiency at lower speeds.

for Fans, Pumps & Compressors

TRI provides variable speed power systems up to 40,000 HP for horizontal or vertical applications, new or retro-fit, and direct or geared systems.

Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings


Phone: (610) 363-8570            Contact Us Fax: (610) 524-6326           TRI Web Site:


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August 1994                     

Dr. Mel Giberson, P.E. - TRI President Announces Recent US Patents Issued to TRI

These are the result of TRI's extensive and intensive efforts over the past 20 years to improve the efficiency and reliability of high power fluid drive, typical of Boiler Feed Pump and Fan applications. Many are also useful when upgrading existing fluid drives for sliding pressure applications and/or high turn-down ratio applications.

5,331,881 Fluid Drive Impellers and Runners machined via 3-D CAM/CNC from alloy steel forgings with integral reinforcing ring and improved vane edge shapes. Increased power and efficiency result from the optimized cavity shapes and stronger vane structure. The multi-axis CAM/CNC machining provides the necessary flexibility to precisely configure the rotating element size to the power requirement.
5,315,825 Fluid Drive Oil System incorporating a circuit oil temperature control valve and separate oil reservoir. This system improves efficiency and reduces oil leakage, foaming, and disposal. 
5,303,801 Fluid Drive Brake System. Large calipers on fold-back/removable arms provide greater breaking power, improve reliability, and simplify maintenance. The conventional master cylinder is replaced by a hydraulic intensifier and oil reservoir allowing the system to work. 
5,207,903  Filter Stand Assembly for the support of conventional filters and double circuit valves incorporating trays for draining used filter elements, and an environmentally friendly pan underneath to contain oil drips and leaks. 
5,188,170  Rocker Connection for Heat Exchangers and Pipes that permits rolling, and not the typical sliding support action. No restraint along the axis of the heat exchanger, and almost rigid support in both transverse directions. 

Contact TRI regarding the availability of site licenses for the above patents.

Call, fax or write for inormation on how these TRI patents can solve the problems on you maintenance list.

TRI offers the following products and services:

  • Align-A-Pad Journal Bearings
  • Seals: Floating Ring, Labryinths
  • Oils Systems: New & Upgrades
  • Fluid Drives: Renewal Parts Rebuilds & Upgrades - All Sizes & Models
  • Thrust Brearings: Equalizing & Non-Equalizing, Tilting Pad, Fixed Geometry
  • Components and Impellers made by multi-axis CNC milling machines
  • Consulting services addressing all rotating machinery, emphasizing control of rotor vibration and performance of journal and thrust bearings.

TRI will be exhibiting at the 23rd Turbomachinery Symposium in Dallas from September 13th to the 15th
Our booth is number 122 - Call for Free Exhibit Area Passes and STOP and SAY HELLO


TRI does answer phone calls and returns Fax Messages

Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings


Phone: (610) 363-8570            Contact Us Fax: (610) 524-6326           TRI Web Site:


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July 18, 1996                     

Technical Notes from Dr. Mel Giberson, P.E. - TRI President

The 750 MW Westinghouse Turbine-Generator Improved

by TRI Manufactured Products and Services consisted of an HP, IP and two LP turbines, a generator and an exiciter.1 All of the original turbine bearings were the OEM’s standard 4-pad design.

Alignment Vibration
Maintenance Instrumentation


  • The entire machine had to be aligned to bearing No.1. This bearing had no provision for making bearing alignment moves.
  • Overall HP rotor vibration.
  • The original design did not provide an easy method of flushing the lube oil supply and drain pipes.
  • No provision was made for blocking the lube oil flow to specific bearings for maintenance.
  • Only one vertical vibration proximity sensor for each bearing. It was located in the pedestal oil seal where seal tooth scratches on the shaft would negatively affect the indicated vibration, providing uncertain balance data.



  • Two TRI Align-A-Pad bearings replaced the original No.1 and No.2 bearings in the HP turbine. Now the No.1 bearing can be aligned independently. Alignment moves can now be made with high reliability and maintain almost 100% contact to the pedestal bore without hand-working the alignment pads.
  • Using proprietary software, TRI tilting pad bearings were designed to minimize rotor vibratory amplitudes. TRI’s bearing design has more tilting pads than the original bearing, and these TRI pads self-align to the shaft under all conditions; even at operating speed. Therefore, no twist and tilt checks are necessary during installation.
  • The thin sheet metal pedestal cover was modified in the TRI shop to provide for rigid external mounting of the "dual vibration probes". These probes read journal motion relative to the bearing and bearing (not pedestal cover) seismic motion. The vibration since start-up has been approximately 1 mil throughout the load range.
  • TRI manufactured "flush cock valves" for 3", 4" and 5" pipe sizes. These valves control the lube oil supply. Each plug has three clearly marked positions: Run, Flush and Block. It is not possible to change the valve position while the lube oil is on.
Contact TRI for detailed information concerning this project or other TRI solutions.

We focus on bearings, rotor-bearing assemblies, rotor vibration control, fluid drives and oil systems. TRI manufactured products provide years of trouble free operation. TRI analyzes, designs, manufactures and installs this equipment.Please advise TRI of any changes of your fax/phone numbers. If you want to receive future issues of TRI Personalized Fax Mail or other TRI communications by Email, drop us a note at E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

TRI answers phone calls, e-mail and fax messages
Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings


Phone: (610) 363-8570            Contact Us Fax: (610) 524-6326           TRI Web Site:


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June 1, 1996                     

Technical Notes from Dr. Mel Giberson, P.E. - TRI President

The facts about Babbitt Bearings:

  • Babbitted bearings are expected to serve for years and years without significant problems

In contrast, rolling element bearings have expected lifetime usually requiring continued replacement.

  • Rotor Vibration: Bearing design usually has a significant influence on rotor vibration.

To change rotor vibration characteristics, consider changing bearing design. A good bearing design can solve problems caused by an unbalanced rotor, sub-synchronous rotor vibration, critical speeds, or vibration problems during start up.


If you are continually servicing your babbitted or rolling element bearings, it’s time to consider the cost. Your cost effective solution is right here. Contact TRI for a bearing design evaluation.

Thousand of megawatts use TRI bearings and related products

Recent TRI Project Achievements: Rotor vibrations of 200 MW GE Turbine-Generator are tamed!!!

The problem: A series of 200 MW GE steam turbine-generators has had rotor vibration problems for years. The HP turbine rotor vibration was particularly susceptible to changes of load, steam conditions and valve position.

The solution: TRI evaluated the problem using TRI proprietary software. The software analyzed the rotor-bearing dynamics. The analysis showed that rotor vibrations were a result of changes in bearing film stiffness during operation. It also indicated that three bearings were most influential.

A new design using three TRI Align-A-Pad bearings in place of the existing tilting pad bearing and two elliptical bearings was implemented. The new bearings were specifically designed with the proper film stiffness.

The result: Low amplitude and steady vibrations over the entire load range

  • TRI Consulting Engineering Services - to solve vibration and bearing problems and to design upgrade
  • Rotor-bearing performance analysis by computer simulation
  • Babbitted journal bearings
  • Align-A-Pad bearings
  • Fluid drives: 1,000 to 30,000+ hp.
  • Full machine shop with 5-Axis CNC capabilities
  • Oil systems for fluid drives, turbines and related equipment
  • Seminars on bearing design and fluid drives
  • Arrange a visit to your plant of TRI’s new Product and Service Display Van
TRI answers phone calls, e-mail and fax messages
Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings


Phone: (610) 363-8570            Contact Us Fax: (610) 524-6326           TRI Web Site:


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April 1995                     

Technical Notes from Dr. Mel Giberson, P.E. - TRI President

Examples of New Solutions for Old Problems. Some may apply to your equipment needs

  • Redesign and Manufacture an Up-rated Vertical Thrust Bearing for a Hydro-electric Generator in the Mid-Atlantic Region. The original thrust bearing with Jack Screw loading feature was put into service in 1913.

    The TRI design of a Self-Equalizing Tilting Pad Thrust Bearing replaces the failed Jack-Screw thrust bearing arrangement. The existing base is modified to accept the new thrust self-equalizing bearing assembly, and a new forged alloy-steel split thrust collar was provided. TRI's cost effective concept cuts days from the installation procedure by eliminating the need to individually "load" each thrust bearing pad. The new design also provides a greater load capacity. The self-equalizing feature accommodates alignment changes due to continued growth and shifting of the dam.

  • Redesign and Manufacture Monolithic Generator Fans to replace Fans of Welded Design for a Mid-west OEM manufacturer of Generators. Each new TRI monolithic fan is made from a single forging without welding.

    TRI performs in-depth Finite Element Analyses for new Fan configurations to determine stress distributions, blade natural frequencies, mode shapes, and endurance limit characteristics. The Fan geometry are modified in response to the FEA results. Alloy steel forging chemical and mechanical properties are selected to suit the environmental conditions. TRI makes the 3-D CAM programs for manufacturing the final products using 5-axis CNC milling machines in our facilities.


  • Redesign and Manufacture Bearing Assemblies for Motors for Boiler Feed Pump Service. New elliptical bore designs significantly reduce vibrations. TRI design features simplify installation and maintenance: have self-aligning capability, accommodate undersize journals (no plating), and avoid babbitt scraping.

  • Remanufacture 15,000 HP Fluid Drives to TRI's latest Heavy Duty design specifications for Boiler Feed Pump Service in sliding pressure service.

    These fluid drives incorporate all tilting pad bearings and new shafting arrangements to minimize shaft vibrations at any operating condition, including start-up. Patented and Proprietary designs, methods, and procedures are employed.

    Technical Seminars in June-July 1995
        Offered Locally in Four Regions of the U.S.
        • Fluid Drives: Design, Operation, Maintenance, Specifying for New Applications, Re-rating Existing Units, Comparison to other Variable Speed Drives. (Mon-Tue)
        • Journal Bearing Design and its influence on performance of rotating machinery in electircal generation plants. (Wed-Thur)
        • Open Forum: Discussion of topics brought to seminar by attendees (Evening & Fri).
        • Details to be provided in TRI's May 95 Personalized Fax Letter.
          Seminar Abstract available upon request.

    These are a sampling of projects which TRI performs for our customers throughout the US and abroad. TRI's approach is to provide services and products that improve the operating reliability and availability of our clients' production facilities in a cost-effective manner. Please contact TRI for innovative solutions to meet your rotating equipment needs.

    Please advise us of changes, additions, or deletions in Fax numbers or mailing addresses for you or your associates by calling 800-363-8570. We thank you for your help in updating our data.

    Call, Fax, or Write for information on how TRI can Help Solve Problems on Your Maintenance List.

    Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings


    Phone: (610) 363-8570            Contact Us Fax: (610) 524-6326           TRI Web Site:


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January 1996                     

Technical Notes from Dr. Mel Giberson, P.E. - TRI President


Factor influencing Fluid Drive Reliability are:

  • Suitability to the application: size, speed, power, turndown ratio.
  • Component design features, materials and details
  • The vibration and temperature monitoring instrumentation
  • Foundation, sole plate, grout and alignment retention
  • Associated equipment: drivers, gears, flexible couplings and loads.
  • Operation practices
  • Rebuild and maintenance practices
  • Scoop tube actuator
  • Oil conditioning system
  • Speed/power control system


  • High vibration in certain load range(s)
  • Sensitivity to misalignment to adjacent equipment
  • Broken vanes in the impeller, runner or vaneplate
  • Poor control of output shaft speed in certain load ranges(s)
  • Oil leakage or oil vapor leakage out of shaft seals or vent
  • Removal of "pilot" bearing, replaced by additional bearing on the output shaft
  • Damaged/worn scoop tubes, scoop tube linkage, slide plates, brackets, etc.
  • Problems with AC/DC oil pump controls, during operation and/or unit trips
  • Repeated damage of journal bearings(s). Need for bearings with undersized bores.
  • Updated and simplified installation, operation and maintenance manuals, in English
  • Vibration and/or temperature sensing/ monitoring/ diagnostic system(s) or current design
  • Replacing an air operated scoop tube actuator with an electrically operated one.
  • Brakes requiring frequent attention. Brakes that will positively stop the fluid drive output shaft.
  • Adaptation of fluid drive instrumentation and controls to the Distributed Control System for the entire unit.
  • Automatic maximum (or minimum) output shaft speed or power required by the existing application, or for a new/revised application.
  • Spare parts problems: Obtaining desired parts that fit properly with acceptable surface finishes; obtaining modified parts made of proper materials to suit your particular application
  • Worn/damaged flexible coupling on input or output end, including the large diaphragm couplings typically used on Westinghouse turbines.

Turbo Research, Inc. has successfully addressed these issues for fluid drives in almost all applications for approximately 25 years. TRI has developed understandings and solutions for these Fluid Drive concerns for all applications, sizes power ratings, speeds and manufacturers, as evidenced by 6 recent U.S. Patents issued to TRI, the leader in Fluid Drive Technology in the U.S. today.

New Fluid Drive Systems for NEW or EXISTING applications designed and built by TRI:

Turbo Research, Inc. designs and manufactures New or Rebuilt FLUID DRIVE SYSTEMS addressing the above concerns so as to be TROUBLE FREE form the INITIAL Start-up. TRI’s facilities are located in Lionville, PA.

New U.S. Patent to be Issued to TRI:

A new U.S. Patent will be issued to TRI for a design of a QUICK DISCONNECT flexible coupling for this application: A rigidly mounted fluid drive which is driven by a flexible coupling connected to an extension shaft mounted in a sliding housing, such as the front end of a GE Large Steam Turbine-Generator. The existing flexible coupling which is located in the nose section of the turbine front standard is removed and the nose is modified slightly. A new disconnect coupling with hydraulic actuating arrangement is installed. This arrangement can operate while the standard slides back and forth as a function of turbine temperature.

Upcoming Exhibition of TRI Engineering Services and Products: The 17th Energy Generation Conference will be held in Bismark, North Dakota on January 16-18, 1996 at the Civic Center. Stop by our Booth #111 and say hello.

Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings


Phone: (610) 363-8570            Contact Us Fax: (610) 524-6326           TRI Web Site:

December 1994                    

Turbo Research Inc. Logo


Looking Forward to 1995. A Note from Dr. Mel Giberson, P.E. - TRI President

          TRI's Mission: Past, Present and Future

  • To control the vibrations of rotating machinery via suitably designed products and/or services: Babbitted journal and thrust bearings; CAM/CNC products such as impellers and fans; new, rebuilt and upgraded assemblies such as fluid drives.

  • To improve the customer’s process operating efficiency, availability, and reliability.

  • To work with our customers to "remove problems for their maintenance lists."

  • To use highly skilled engineers and technical personnel, and only the best materials and state-of-the-art manufacturing processes, tooling and equipment.

  • To develop new products and services to meet the changing needs of our customers.

  • To operate TRI with an Engineering "bottom line."

  • To offer reasonable pricing for the high quality standards of TRI’s products and services which our customers know, respect, expect and deserve.

OBJECTIVES of TRI’S personalized Fax Letters
  • To provide insight into technical problems or subjects of braod interest to the Rotating Machinery Industry today.

  • To discuss symptoms of and concerns about the problem, as well as the causes and cures.

  • To provide a "clearinghouse" for information to assure users/owners/operator that a specific vibration problem, bearing damage problem, or difficult operating characteristic is not likely to be unique to their equipment. Others, almost always, are experiencing/have experience the same problem. In addition, proven solutions are presented and discussed.

          Past Copies of the TRI personalized Fax Letters are available

    June - Steam Turbine Journal Bearings
    July - Does your Rotating Equipment Eat Bearings
    August - TRI Recent Patents
    September - Sliding Pressure Operation
    October - A Reality Check for the Rotating Machinery Industry Today
    November - Bearing Designed for Large Vertical Misalignment Conditions.

If you would like a copy of any or all of these, please let us know. Call us as (800) 363-8571.
Future editions will address case histories, upgrades, retrofits, and new technologies to solve existing problems.
We would like to update your Fax Number and Mailing Address in our records.
Please advise us of any change in Fax Number of Mailing Address for you and your associates.

Seasons Greetings to All of Our Customers. Thank you for your business.

Over 15,000 MW of Electrical Generation Depend Upon TRI Bearings


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Phone: (610) 363-8570           TRI E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it. Fax: (610) 524-6326           TRI Web Site:

Improved Journal Bearings for Nuclear Powered Turbine-Generators.

Controlling Sub-Synchronous Vibration

TRI Journal Bearings use upgraded designs and materials to improve rotor vibration control, bearing performance, and bearing life for large, heavily loaded journal bearings in nuclear powered 1800 rpm turbine-generators, as well as in large fossil powered units.

TRI uses computer simulations to evaluate the parameters of heavy loaded bearings often found in nuclear powered turbine-generators. A vertically integrated process that goes from analysis and design to manufacturing and installation has resulted in an enviable experience record for both fixed bore bearings and tilt pad bearings. In the design process, TRI uses its proprietary computer programs to adjust the design in order to optimize oil film thicknesses, film pressures, bearing metal temperatures, and power losses, and at the same time, to suppress sub-synchronous rotor vibrations over the load range of the bearing application.  For bearings from other manufacturers  that have been damaged in service and are being repaired at TRI, we  often propose design adjustments based on the results of TRI’s computer simulations.


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