Refurbishing  a TRI Align-A-Pad Journal Bearing Setting the Assembled Clearance

This photo shows a 17” diameter TRI Tilting Pad Bearing for an Allis-Chalmers Turbine that has been retrofitted for TRI bearings with ears, as discussed in the Section on TRI design principles.  The bearing is shown in the process of being refurbished after many years in service.   The pads have already been rebabbitted and remachined to suit the journal diameter. Knowing the journal diameter and pad thicknesses, the shimplates are ground to prescribed thicknesses to give the specified assembled clearance for each pad.

 

 

 

 

Refurbished or New GE-style  Tilting Pad  Journal Bearings

This photo shows the lower half of a GE-style 6-pad “double-tilt” tilting pad journal bearing.  Based on specific field measurements, TRI designed and built this bearing with upgrades as requested by the customer. It is a replacement bearing in a turbine made by a GE licensee.   TRI can also refurbish/ renew existing GE-style tilting pad bearings with various upgrades to minimize wear of the contact surfaces of pad backs and housing bores, extending the lives of these turbines.

 

 

 

 

Replacement Tilting Pads for a  Westinghouse Turbine

The set of four steel-backed tilting pads shown in this photo was designed and manufactured by TRI  based on specific field measurements.   These four new pads can be used to replace existing pads of a 4-pad Westinghouse turbine bearing, one pad at a time or all four pads together.   TRI can refurbish Westinghouse tilting pad bearings by rebabbitting and reboring existing pads, if this is what the customer desires.   Note that TRI offers an option of replacing an entire bearing with a TRI Align-A-Pad® Bearing which will provide improved rotor vibration performance.

 

 

 

 

Replacing GE 4-axial  Groove Journal Bearings with TRI Elliptical Bore Journal Bearings

Shown here is a typical GE 4-axial groove journal bearing with a commonly observed wear pattern that leads to high bearing oil film and bearing metal temperatures. Wear, generally related to turning gear wear and/or particulate matter, erodes the Babbitt surface adjacent to the axial groove on the down-coming side, in this case, the right side in this picture.  This reduces the film thickness at the edge of the feed groove and limits the lube oil entering the film.  If not recognized, slight additional wear can easily stop the lube oil entering the film, resulting in severe bearing damage, possibly a major Babbitt wipe.

 

 

 

 

Replacement TRI Elliptical  Journal Bearing

This photo shows an elliptical bearing with only two oil supply feed grooves, one on each side at the horizontal joint.   Two important advantages of this elliptical bearing are that even severe turning gear wear in the bottom half will not shut off the lube oil supply to the oil film, and the active bearing length can be made longer because the elliptical design maintains greater rotor stability (control of subsynchronous rotor vibration) compared to the circular bore 4-axial groove design shown above.

 

 

Rebabbitt and  Rebore  Large Bore Journal Bearings

One of TRI’s major services for power plants is to provide round the clock support for refurbishing Babbitted journal bearings, from 2 inches to over 30 inch bore diameter.   Shown here is a 30 inch bore bearing for a nuclear powered generator that TRI refurbished recently.   TRI can centrifugally cast bearings, or if the Babbitt to steel bond is acceptable, the bearing can be hand Babbitt welded minimizing the need to reround the bearing extensively.

 

 

 

 

 

 

Rebabbitt and Rebore Cast Iron  or Cast Steel Fan Bearings

TRI rebabbitts and rebores fan bearings, whether the housing is cast steel or cast iron.  Cast Iron housings are more challenging. The original bore geometry or an upgraded elliptical bore geometry with improved oil distribution can be machined. In most  cases, provisions for oiling rings are retained. In other cases, pressure-fed oiling features are added.  

 

 

 

 

 

GE LM 6000 Generator Journal Bearing

The standard Journal Bearing is a 4-pad arrangement as shown in this photo.  It has an unusual bearing support in that the contact surface of the pad is a barrel-shaped roller integral to the pad.  The barrel is smaller at the ends than in the center permitting accommodation of a small amount of tilt and twist. The barrel slides in the slot as the pad tilts to form an oil wedge.   TRI has developed the tooling and fixtures necessary to rebabbitt and remachine the pads and to assemble the entire bearing. Hence, turnaround time is only a few days. TRI’s process can be adjusted for the current journal diameter, should remachining the journal be necessary.

 

 

 

 

Rebabbitt and  Rebore  Large Bore Journal Bearings Having Unusual Bore Geometries

The Journal Bearing shown in this photo is a fixed bore bearing 550 mm (21.65 inches) in diameter.  It was manufactured by MAN Turbines in Germany in the 1970s.  The bearing has an unusual bore geometry, three arcs:  The bottom arc is 180 degrees. The two arcs in the top half are 90 degrees each.

The top arcs have machining shims that are uniform in thickness to provide the desired machined curvature.  Running shims are inserted behind the arcs to provide the desired converging oil film wedges.  All three arc centers are separated from each other. 

TRI’s proprietary journal bearing simulation program  models this bearing accurately, giving TRI the confidence that this MAN bearing will function as intended when TRI completes the rebabbitting and remachining processes.

With TRI’s engineering skills and excellent computer programs, TRI can simulate a wide range of bearing bore geometries.  Hence, TRI can either refurbish or make new journal bearings of unusual bore geometry with confidence to meet the needs of our customers.

Rebabbitt and CNC Machine  6 Offset Arcs in a Brass Bearing

TRI rebabbitted and then remachined 6 offset arcs in this bearing using our CNC horizontal boring mill, duplicating the OEM design. This design attempts to duplicate the angular tilting of a tilting pad bearing to provide 6 oil films with a pressure distribution in each arc to centralize the journal when rotating. The trailing edges of the arcs are quite delicate and can be worn away under certain circumstances. TRI can renew these bearings and can make new ones for those machines that use bearings of this design.