Product Support Program For Installing An Improved Bevel Gear Set On Certain TH62 Telehandlers Caterpillar

NOTE: The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.

NOTE: This Program can be administered either before or after a failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS4036" as the Part Number and "7755" as the Group Number. If administered before failure, use "56" as the Warranty Claim Description Code and use "T" as the SIMS Description Code. If administered after failure, use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.

Termination Date

Problem

Failure has been reported of the 1372542 Front Axle Bevel Gear in the TH62 Telehandler. Failures have been confined to machines with the 4TM prefix operating in arduous agricultural application.

Affected Product
Model & Identification Number

TH62 (4TM1-422, 4TM425-453, 4TM455-459, 4TM462-489, 4TM491-509, 4TM511-521, 4TM525-538, 4TM540, 4TM541, 4TM543-545, 4TM547-556, 4TM558-575 , 4TM577-584, 4TM586, 4TM588-595, 4TM597-606, 4TM608-640, 4TM642-646 , 4TM648-663, 4TM665-668, 4TM670-678, 4TM680-684, 4TM686-707 , 4TM709-740, 4TM742-759, 4TM761-772, 4TM774, 4TM775, 4TM778-781 , 4TM784, 4TM785, 4TM787-808, 4TM810-824, 4TM826-841, 4TM844 , 4TM845, 4TM847, 4TM848, 4TM850-853, 4TM855-912)

Parts Needed

1 - 1475322 Kit-Shot Peened

The following parts are included in the 1475322 Kit.

2 - 8I3852 O-Ring

1 - 8Q2151 Plug

2 - 975144 O-Ring

16 - 975184 Bolt

16 - 975185 Washer

1 - 975215 Seal

1 - 975218 O-Ring

1 - 1464091 Bevel Set

- various selection of shims

Action Required

NOTE: This procedure applies to the front axle only.

Remove the 1372542 Bevel Gear Set and replace it with a 1475322 Kit. This kit contains a new bevel set and enough new parts to rework "Before Failure". If reworked "After Failure" other parts required will need to be identified and obtained from the parts system.

NOTE: Removal and refitting of the differential is covered in Disassembly & Assembly SENR5840. Adjustment of the bevel gear set is covered in the rework procedure of this letter. "After Failure" rework must stamp the letter "R" after the part number on the serial number plate.

See the attached procedure.

Service Claim Allowances

NOTE: This is a 7.5-hour job.

Parts Disposition

Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

Attach.

(1-Rework Procedure)

Rework Procedure

Differential Adjustments

The following procedures detail adjustments to the differential which are necessary during assembly.

NOTE: The bevel gear and pinion are a matched set. If either part is worn or damaged both parts must be replaced with a matched set.

Pinion Depth Adjustment

NOTE: The pinion depth adjustment procedure is only necessary if the axle carrier or the bevel gear and pinion set is replaced.

Pinion Arrangement

(1.) Axle casing (2.) Shim pack (pinion depth adjustment) (3.) Ring nut (4.) Outer bearing (5.) Spacer (6.) Shim pack (pinion pre-load adjustment) (7.) Inner beading (8.) Pinion

Before the pinion assembly is installed into the differential housing, the correct pinion depth must be established. Pinion depth is controlled by the thickness of shim pack (2). The formula used to determine the required shim pack thickness is: (2) = W + X

Pinion Marking

The pinion has EITHER: A figure specific to that pinion marked on the pinion head, OR a nominal figure of 1 1 3.00 marked on the pinion shaft and a plus or minus symbol stamped on the end of the pinion shaft.

Pinion Marking - either on face of pinion (A) or shaft and shaft end face (B) & (C)

'W' is calculated from the marking on the pinion head of shaft.

'X' is determined by a measurement taken on the axle casing (1).

Examples of each of the pinion marking methods are given in the following procedure.

1. If the marking is on the pinion head at (A) it will have 5 digits, 11 2.98 or similar, subtract this from a nominal of 113.00, and record as dimension W.

If the marking is on the pinion shaft at (B) it will have 3 digits, 0.02 or similar, if so check the end of the shaft at (C) for the symbol. If stamped with a (+) symbol, record the 3 digit number as negative (-) for dimension W.

If the shaft is marked with a (-) symbol at (C), record the 3 digit number as positive (+) for dimension W.

Depth Gage Set-Up

2. Position tooling A on a surface plate. Set the dial indicator gauge to zero. Dial indicator base should be in recess.

Bearings installed with measuring bar and bar cap

Use the measuring bar and bar cap from tooling B to Install bearings (4) and (7) into the axle housing. Do not install spacer (5) or shim packs at this stage.

Measuring dimension X using tooling B

3. Attach remainder of tooling B. Install the dial indicator with the extension point passing through the larger hole in the datum bar. Slide the indicator on the datum bar to sweep the extension point across the INNER bore of the axle casing. Record the LOWEST reading as dimension X.

4. Remove tooling B.

Position of shim pack (2)

5. Add together dimensions 'W'and 'X' and make up a shim pack (2) of equal thickness. This shim pack will be installed in the position shown with tooling in the following topic, and with the pinion in final assembly.

Pinion Bearing Pre-load Adjustment

Position of pinion bearing pre-load shim pack

The pinion bearing preload is determined by the thickness of a shim pack (6) installed on the pinion shaft between the inner race of bearing (7) and spacer (5). The following procedure describes how to calculate the thickness required.

Measuring dimension Y using tooling B

1. Install bearings (4) and (7), and shim pack (2), made up in step 5. of the Pinion Depth Adjustment procedure, into axle housing with tooling B, measure and note dimension Y.

2. Remove the tooling and bearings from the axle housing, leave the bearing cups and shim pack in position.

Measuring dimension Z using tooling C (4.) Beading (5.) Spacer (7.) Bearing

3. Assemble bearings (4) and (7), spacer (5) and tooling C.

4. Measure and make a note of dimension Z.

5. To obtain the shim pack thickness required to obtain the correct pre-load, subtract dimension Y from dimension Z and add, 0. 1 0 to 0. 1 2 mm (.004 to .005 inch).

6. Make up shim pack (6) as required. Shims are available in thicknesses of: 0.35, 0.40, 0.45, 0.50, 0.55 and 0.60 mm (0.01 4, 0.016, 0.018, 0.020, 0.022 and 0.024 inch).

(1.) Axle casing (2.) Shim pack (pinion depth adjustment) (3.) Ring nut (4.) Outer bearing (5.) Spacer (6.) Shim pack (pinion per load adjustment) (7.) Inner bearing (8.) Pinion

7. Install pinion (8) with bearings (7) and (4), spacer (5), shim pack (6) and ring nut (3).

8. Tap the end of the pinion shaft with a soft faced hammer to seat the parts, and tighten ring nut (3) to a torque setting of 500 to 540 N·m (370 to 400 lb ft) using tooling D.

NOTE: Do not exceed 540 N·m or damage to the bearing may result.

Pinion rolling torque check

9. Rotate the pinion bearing several times and then check the rolling torque using tooling E. This should be 1.2 to 1.7 N·m (1 1 to 15 lb In). If the torque is incorrect, increase the thickness of shim pack (6) to lower the torque or decrease the thickness of the shim pack to increase the torque.

10. When the correct rolling torque is achieved, remove ring nut (3), apply 9S-3262 to the threads of the pinion shaft, Install the ring nut and tighten to a torque of 500 to 540 N·m (370 to 400 lb ft).

NOTE: Do not exceed 540 N·m or damage to the bearing may result.

Differential Backlash and Tooth Engagement Contact Pattern Adjustment

Differential

(1.) Differential housing (2.) Ring gear (3.) Bolts (4.) Bolts (5.) Differential gears (6.) Pinion gears (7.) Side gears (8.) Ring nut (9.) Ring nut (10.) Bolts (11.) Supports (12.) Differential case cover

1. Install ring gear (2) on differential case (5). Apply 9S3263 Thread Lock to the threads of bolts (4). Tighten the bolts to a torque of 73 to 76 N·m (52 to 56 lb ft). Install side gears (7), pinion gears (6), the thrust washers and pins into the differential case.

2. Install cover (12) on the differential case. Apply 9S3263 Thread lock to the threads of bolts (3). Tighten the bolts to a torque of 120 to 123 N·m (90 to 92 lb ft).

3. Install the differential case assembly and bearings into the differential housing (1). Install ring nuts (8) and (9). Tap with a soft faced hammer to seat the parts. Install a dial indicator against ring gear (2) and tighten ring nuts (8) and (9) equally with tool E until there is a minimum backlash of 0. 1 5 mm (.006 inch).

Differential rolling torque check

4. Check the torque necessary to rotate the pinion as shown. As an example, if the torque reading is 1.8 N·m (16 lb in):

Tighten ring nut (9) with tool E opposite the ring gear until the torque required to rotate the pinion increases by 3.5 to 4.5 N·m (31 to 39 lb in). In this example the rotating torque would be approximately 5.8 N·m (52 lb in).

Examples of incorrect tooth contact patterns and the direction in which components must be moved to achieve correct tooth contact

5. Check the tooth contact pattern of the pinion and ring gear as follows. Apply marking compound such as red lead or Prussian blue to the ring gear. Rotate the pinion clockwise and counterclockwise until all of the teeth on the ring gear have made contact with the pinion in both directions.

a. To move the ring gear towards the pinion, ring nut (8) must be tightened, and ring nut (9) loosened. Each ring nut must be turned the same amount.

b. To move the ring gear away from the pinion, ring nut (8) must be loosened, and ring nut (9) tightened. Each ring nut must be turned the same amount.

c. To move the pinion towards the ring gear, pinion cover shims must be removed. (see Pinion Depth Adjustment).

d. To move the pinion away from the ring gear, pinion cover shims must be added. (see Pinion Depth Adjustment).