Introduction

NOTE: For Specifications with illustrations, make reference to the POWER TRAIN SPECIFICATIONS for 910 WHEEL LOADER, Form No. REG01252. If the Specifications in Form REG01252 are not the same as in the Systems Operation and the Testing and Adjusting parts of this book, look at the printing date on the back cover of both books. Use the Specifications given in the book with the latest date.

Problem Solving

Use this as a reference for the location and correction of problems in the power train. When more checking is necessary, use the 7S8875 or 8M2736 Hydraulic Test Box and the 3P2247 Transmission Test Cover. Locations of the pressure taps, and procedures for testing and adjusting are given in the 910 POWER SHIFT TRANSMISSION TESTING AND ADJUSTING, Form No. REG01237.

Always make visual checks first. Then check the operation of the machine and go on to check with the instruments.

Visual Checks

1. Check the oil level in the transmission.

2. Check all oil lines, hoses and connections for leaks and damage. Look for oil on the ground under the machine.

3. Move the control lever to REVERSE and all FORWARD positions. The detents must be felt in all positions.

4. Let the oil out of the screen housing. Remove and check the screen for loose particles.

a. Fiber particle give the indication of damage to the clutches in the transmission.

b. Shiny steel particles give the indication of a pump failure.

c. Rubber particles give the indication of a rubber seal or hose failure.

If you find rubber or metal particles, all components of the hydraulic systems must be washed clean. Do not use parts with damage. Use new parts.

Checks During Operation

With the engine running, move the selector lever to all speed positions. The detents must be felt in all positions.

Operate the machine in each direction and in all speeds. Make note of all noises that are not normal and find their sources. If the operation is not correct, make reference to the CHECK LIST DURING OPERATION for "problems" and "probable causes".

Check List During Operation

Transmission

PROBLEM: Transmission does not operate in any speed or does not engage (slips) in all speeds.

PROBABLE CAUSE:

1. Low oil pressure caused by:

a. Low oil level.

b. Control linkage loose or adjustment not correct.

c. Failure of the oil pump or the pump drive.

d. Air leaks on inlet side of pump.

e. Leakage inside the transmission.

f. Adjustment of the modulating relief valve not correct, or valve does not close.

g. Load piston not closing.

2. Mechanical failure in transmission.

3. Failure of torque converter.

4. Failure of the bevel pinion or the bevel gear.

PROBLEM: Transmission does not shift.

PROBABLE CAUSE:

1. Low oil pressure.

2. Air leaks on inlet side of pump.

3. Control linkage loose or adjustment not correct.

PROBLEM: Transmission engages very suddenly (rough shifting).

PROBABLE CAUSE:

1. Primary setting of the relief valve not correct.

2. Adjustment of control linkage not correct.

3. Load piston not closing.

4. Valve springs that are weak or have damage.

PROBLEM: Slow shifting.

PROBABLE CAUSE:

1. Low oil pressure.

2. Inside and outside linkages adjustment not correct.

3. Air leaks on inlet side of pump.

4. Load piston not closing.

PROBLEM: Transmission does not operate in first speed.

PROBABLE CAUSE:

1. No. 4 clutch not engaged (slips) because of:

a. Low oil pressure.

b. Discs and plates have too much wear.

PROBLEM: Transmission does not operate in second speed.

PROBABLE CAUSE:

1. No. 2 clutch not engaged (slips) because of:

a. Low oil pressure.

b. Discs and plates have too much wear.

PROBLEM: Transmission does not operate in third speed.

PROBABLE CAUSE:

1. No. 1 clutch does not engage (slips) because of:

a. Low oil pressure.

b. Discs and plates have too much wear.

PROBLEM: Transmission does not operate in reverse.

PROBABLE CAUSE:

1. No. 3 clutch does not engage (slips) because of:

a. Low oil pressure.

b. Discs and plates have too much wear.

PROBLEM: Transmission does not shift out of a speed and/or direction when the shift lever is moved to NEUTRAL.

PROBABLE CAUSE:

1. Control linkage having damage or wrong adjustment.

2. Clutch not releasing.

PROBLEM: Transmission engages, torque converter stalls and the engine has a load condition. Machine does not move.

PROBABLE CAUSE:

1. Mechanical failure in the transmission.

a. Parts that have damage.

b. A clutch not correctly engaged.

2. Failure of the bevel gear or the bevel pinion.

3. Failure in the final drive.

PROBLEM: Transmission gets hot.

PROBABLE CAUSE:

1. Bad temperature gauge.

2. Low oil level.

3. Core of oil cooler not completely open.

4. Too much resistance in the clutch.

5. Low oil flow as a result of pump wear or extra leakage in hydraulic system.

PROBLEM: Pump noise not normal.

PROBABLE CAUSE:

1. Loud sounds at short intervals that give indication that particles are going through the pump is caused by pump cavitation.

2. A constant loud noise is an indication of pump failure.

Torque Converter

PROBLEM: Torque converter gets too hot.

PROBABLE CAUSE:

1. Operation of machine not correct. Constant overload.

2. Bad temperature gauge.

3. Mechanical failure of torque converter.

4. Too much oil in torque converter housing because of leakage through the torque converter.

5. Supply of oil to the torque converter is low because of:

a. Too much leakage in the transmission.

b. Bad pump.

c. Inlet valve for torque converter not working correctly.

d. Core of oil cooler not completely open.

Differential And Bevel Gear

Adjustment Procedure

1. Make adjustment to the pinion shaft (1) with shims (5) to get .000 to .002 in. (0.00 to 0.05 mm) end play.

2. Install assembly for pinion shaft into differential housing (5).

3. Install the differential carrier assembly with bevel gear (4) so there is a small amount of free movement (backlash) between bevel gear (4) and pinion shaft (1).

DIFFERENTIAL AND BEVEL GEAR
1. Pinion shaft. 2. Shims. 3. Adjustment nut for bearing of bevel gear shaft. 4. Bevel gear. 5. Shims. 6. Housing for differential carrier. 7. Adjustment nut for bearing of bevel gear shaft.

4. Remove assembly for pinion shaft and make adjustment to bearing preload of carrier assembly by turning nut (3) or (7) until the torque needed to turn differential assembly is 15.05 to 20.40 lb. in. (17.4 to 23.5 cm.kg).

5. Install assembly for pinion shaft using the amount of shims (2) necessary to make correct alignment of the heels of the gears.

6. Turn nut (3) and (7) the same amount, with no change to the carrier assembly bearing preload, until the free movement (backlash) between the bevel gear (4) and the pinion shaft (1) is .006 +.005 or -.002 in. (0.15 +.013 or -0.05 mm).

7. Check for correct tooth contact between bevel gear and pinion. Do Steps 5 and 6 again as necessary.

Bevel Pinion Location

1. If the same pinion shaft is installed, use the same shims that were removed.

2. Find the pinion location by looking at the tooth contact pattern made by the teeth of the bevel gear. This can be done in the following way.

ALIGNMENT OF BEVEL GEAR AND PINION

3. Use necessary shims to make alignment of the heel ends of the bevel gear and the teeth of the pinion gear. This will put the pinion in the near correct location with the bevel gear.

4. Make adjustment to the free movement (backlash) of the bevel gear. See the ADJUSTMENT PROCEDURE. This will give a very close adjustment.

5. Make further checks of the adjustment by putting Prussian blue, red lead or paint on the teeth of the bevel gear.

6. Turn the pinion and bevel gear to give a pattern of the tooth contact on the teeth of the bevel gear. Correct tooth contact starts near the toe and goes approximately 30 percent of the length of a bevel gear tooth.

CORRECT TOOTH CONTACT

7. Make adjustment to the location of the pinion shaft if tooth contact is more on one side of a tooth or is near the heel of a tooth.

8. Add or remove shims to move the pinion shaft.

9. Make adjustment to the free movement (backlash) of the bevel gear.

10. Make another pattern of tooth contact (see Steps 5 and 6).

11. If necessary, make several adjustments to the pinion and the bevel gear to get correct tooth contact and free movement (backlash).

Nospin Differential Test

If properly assembled and installed, the rotating wheel should turn freely in both directions [illustrations (3 and 7) and (4 and 8)] until the direction of rotation is reversed unless reverse pressure on the opposite wheel is released.

A slight sound (indexing or clicking) may or may not be heard as the driven clutch alternately disengages from the spider and then engages again with the spider during the time the wheel is turning.

When the direction of rotation is reversed, the clutch will again engage and a slight noise may be heard.

If you do hear repeated loud (indexing or clicking) sounds when checking, then one of the holdout ring and clutch assemblies may not be properly assembled to the spider.

If either wheel does not turn freely in both directions, recheck each step in the installation procedure. Also check both hand and foot brakes for possible drag caused by improper adjustment. Check again to be sure that all thrust washers have been removed.

1. Raise the front axle from the floor so tires are completely free.

2. Put the parking brake on.

3. See Illustration 1. Start the test by turning both wheels in a forward direction as far as possible (normally, both wheels will stop after turning only a few inches).

4. See Illustration 3. With one person holding the right wheel forward (at the point it stopped turning), turn the left wheel toward the rear. You may hear a slight sound (indexing or clicking sound) at regular intervals. The right wheel must be held completely against the point it stopped turning or the left wheel will not disengage freely (become not engaged).

5. See Illustration 5. Turn both wheels toward the rear as far as possible (both wheels will stop after turning only a few inches).

6. See Illustration 7. With a person on the opposite side tightly holding the right wheel toward the rear (at point it stopped turning), turn the left wheel forward. You may hear a slight sound (indexing or clicking sound) at regular intervals. The right wheel must be held completely at the point it stopped turning or the left wheel will not disengage freely (become not engaged).

7. Repeat Steps 3, 4, 5 and 6 (See Illustrations 2, 4, 6 and 8) except this time hold the left wheel at the point it stopped turning (See Illustrations 4 and 8). Turn the right wheel to the rear (See Illustration 4) and forward (See Illustration 8) while listening for the clicking sounds.

TESTING NOSPIN DIFFERENTIAL