R2900G Load Haul Dump Power Train Caterpillar

Illustration 1	g01038877
Schematic for the transmission hydraulic system (neutral, engine stopped) (1) Solenoid valve (for the Number 2 clutch) (2) Solenoid valve (for the Number 3 clutch) (3) Transmission oil cooler (4) Transmission lubrication passage (5) Solenoid valve (for the Number 6 clutch) (6) Solenoid valve (for the Number 1 clutch) (7) Solenoid valve (for the Number 5 clutch) (8) Solenoid valve (for the Number 4 clutch) (9) Torque converter outlet relief valve (10) Torque converter updrive gear case (11) Flow control orifice (12) Torque converter (13) Slug (14) Torque converter ratio valve (15) Slug (16) Modulating relief valve (17) Second speed and fourth speed selector spool (18) Port for Number 3 clutch (19) Direction selector spool (20) Port for Number 5 clutch (21) Port for Number 2 clutch (22) Port for Number 1 clutch (23) Pressure differential valve (24) Transmission oil filter (25) Transmission charge pump (26) Port for Number 6 clutch (27) Load piston (28) Orifice (29) Suction screen and magnet (30) Transmission hydraulic oil reservoir (31) Port for Number 4 clutch (32) First speed and third speed selector spool (A) Transmission lubrication pressure tap (B) Torque converter inlet pressure tap [P3] (C) Torque converter outlet pressure tap (D) Speed clutch pressure tap [P1] (E) Transmission charge pump pressure tap (F) Direction clutch pressure tap [P2]

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. Prevent possible injury by performing the procedure that follows before working on the machine.

Machine Preparation

1. Park the machine on a smooth level surface clear of obstructions and personnel.

2. Shift the transmission direction and speed control to the NEUTRAL position.

3. Lower the work tool to the ground.

4. Engage the parking brake.

5. Place blocks in front of the wheels and behind the wheels.

6. Stop the engine.

7. Install the steering frame lock.

8. Remove the front axle shafts and rear axle shafts except for stall tests.

   Reference: Refer to Disassembly and Assembly, Power Train, "Axle shaft - Remove and Install" for the machine that is being serviced.

9. Allow only authorized personnel on the machine. Keep unauthorized personnel off the machine and in clear sight of the operator.

Test Procedures

Note: All tests and all adjustments must be made while the transmission oil is at normal operating temperature.

Test for the Lubrication Oil Pressure

Illustration 2	g01045706

The pressure tap for transmission lubrication (A) is located on the left side of the transmission.

1. Remove the sampling valve, the adapter and the O-ring seal.

2. Install 6V-3965 Fitting As and 3J-1907 O-Ring Seal.

3. Install the correct hose assembly from 1U-5482 Pressure Adapter Group on pressure tap (A). Attach the opposite end of the hose assembly to the 0 to 400 kPa (0 to 58 psi) pressure gauge in the 1U-5481 Pressure Gauge Group.

4. Start the engine and operate the engine at high idle. Observe the pressure gauge. With the oil at normal operating temperature, the pressure reading of the lubrication oil must be within the values that are found in Table 4.

5. Remove 6V-3965 Fitting As and the 3J-1907 O-Ring Seal.

6. Install the O-ring seal, the adapter and the sampling valve.

Test for the Torque Converter Outlet Relief Valve Oil Pressure

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Illustration 3	g01045126
(C) Pressure tap for the torque converter outlet oil

1. Install the correct hose assembly from 1U-5482 Pressure Adapter Group on pressure tap (C). Attach the opposite end of the hose assembly to the 0 to 1000 kPa (0 to 145 psi) pressure gauge in the 1U-5481 Pressure Gauge Group.

2. With the oil at normal operating temperature, refer to the information in Table 4 for the correct procedure and the correct pressure reading of the torque converter outlet oil.

Test for the Transmission Clutches and Pump Output

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Illustration 4	g01045125
Transmission hydraulic control (B) Pressure tap for converter inlet (P3) (D) Pressure tap for speed clutch (P1) (F) Pressure tap for direction clutch (P2) (G) Plug for load piston (LP)

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Illustration 5	g02330694
(E) Pressure tap for the transmission oil pump

1. Install the correct hose assembly from 1U-5482 Pressure Adapter Group on the following pressure taps: (D), (E) and (F). Attach the opposite end of the hose assembly to the 0 to 3400 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group.

2. Start the engine and operate the engine at low idle. Depress the right service brake pedal and hold down the right service brake pedal.

3. Shift the transmission direction control to the NEUTRAL position. Disengage the parking brake. Shift the transmission speed control to first speed. Watch the pressure gauges. Shift the transmission direction control from the NEUTRAL position to the FORWARD position. Increase the engine speed to high idle. Make sure that the transmission oil is at normal operating temperature. The needle on the pressure gauge for the Number 2 clutch should rise. The needle on the pressure gauge for the Number 6 clutch should rise. The pressure readings must be within the values that are found in Table 4.

   With the transmission in the FORWARD position, shift through the remaining forward speeds and return to the FIRST SPEED position. Use the transmission speed control to change speeds. The pressure reading for each energized clutch must be within the values that are found in Table 4. This checks the pressure of all the speed clutches.

4. Perform Step 3 for all reverse speeds. The same pressure readings should be noted in all reverse speeds.

Test for the Torque Converter and Updrive Lubrication Pressure

Illustration 6	g02330695
(H) Pressure tap for the torque converter and updrive lubrication pressure

1. Install the correct hose assembly from 1U-5482 Pressure Adapter Group on pressure tap (H). Attach the opposite end of the hose assembly to the 0 to 3400 kPa (0 to 580 psi) pressure gauge in the 1U-5481 Pressure Gauge Group.

   Note: The axle shafts can remain installed for this test.

2. Start the engine and operate the engine at high idle. Observe the pressure gauge. With the oil at normal operating temperature, the pressure reading of the lubrication oil must be within the values that are found in Table 3.
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   Table 3

   Torque Converter and Updrive Lubrication Pressure
   Torque Converter and Updrive Lubrication Pressure	(H)		This pressure is 1790 ± 205 kPa (260 ± 30 psi). The axle shafts can remain installed for this test.	None

Transmission Pressures

Adjustments for the Transmission Pressures

Illustration 7	g01045129
Outlet relief valve for the torque converter (1) Torque converter outlet relief valve (2) Shims

Illustration 8	g01045130
Transmission selector and pressure control valve (3) Load piston (4) Shims