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| Illustration 1 | g02699679 |
Schematic for the Transmission Hydraulic Control (1) Number 2 clutch solenoid (2) Number 3 clutch solenoid (3) Priority valve (4) Number 1 clutch solenoid (5) Number 5 clutch solenoid (6) Number 4 clutch solenoid (7) Flow control orifice (8) Lockup clutch solenoid valve (if equipped) (9) Impeller clutch solenoid valve (10) Slug (11) Converter inlet ratio valve (12) Slug (13) Modulating relief valve (14) Direction selection spool (15) Torque converter (16) Lockup clutch (if equipped) (17) Impeller clutch (18) Selector spool for first speed and for third speed (19) Pressure differential valve (20) Load piston (21) Flow control orifice (22) Selector spool for second speed (23) Transmission oil filter (25) Flow control orifice (26) Oil pump (27) Torque converter outlet relief valve (28) Oil cooler (29) Magnetic Screen (30) Lubrication passage for transmission (31) Reservoir (32) Reservoir (A) Oil pump output pressure tap (B) Pump pressure tap (C) Pressure tap for lockup clutch (if equipped) (D) Torque converter inlet pressure tap P3 (E) Speed clutch pressure tap P1 (F) Pressure tap for impeller clutch (G) Direction clutch pressure tap P2 (H) Pump pressure tap (I) Torque converter outlet pressure tap (J) Transmission lubrication pressure tap | |
| NOTICE |
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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates. |
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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. |
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- Park the machine on a smooth level surface.
- Shift the STIC transmission direction control switch to the NEUTRAL position.
- Lower the bucket and/or the attachment to the ground. Lower the blade and/or the attachment to the ground.
- Engage the parking brake.
- Place blocks in front of the wheels and behind the wheels.
- Install the steering frame lock.
- Remove the front axle shafts and rear axle shafts except for stall tests.
- Allow only authorized personnel on the machine. Keep unauthorized personnel off the machine and in clear sight of the operator.
Note: All tests and all adjustments must be made while the transmission oil is at normal operating temperature.
| NOTICE |
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Do not connect or disconnect hose fittings to or from the quick disconnect nipples when there is pressure in the system. This will prevent damage to the seals that are in the fitting. |
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The drive shaft rotates between the torque converter and the transmission whenever the engine is running. Contact with the rotating shaft can result in personal injury or death. The rotating shaft is located under the implement and steering pumps. Do not allow personnel into the pump bay area behind the cab when the engine is running. |
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| Required Tools | ||
| Part Number | Description | Quantity |
| 1U-5481 | Pressure Gauge Group | 1 |
| 1U-5482 | Pressure Adapter Group | 1 |
Test Procedures
Use the following procedure in order to check the following pressures: direction clutch oil, speed clutch oil and oil pump output.
| Transmission Speed Selection | Engaged Clutches |
| Third Speed Forward | Number 2 and Number 3 |
| Second Speed Forward | Number 2 and Number 4 |
| First Speed Forward | Number 2 and Number 5 |
| Neutral | Number 3 |
| First Speed Reverse | Number 1 and Number 5 |
| Second Speed Reverse | Number 1 and Number 4 |
| Third Speed Reverse | Number 1 and Number 3 |
- Install the correct hose assembly from 1U-5482 Pressure Adapter Group on the following pressure taps: (A) , (E) and (G) . 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 .
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| Illustration 2 | g00412026 |
992G Wheel Loader and 854G Wheel Tractor Transmission (A) Speed clutch pressure tap P1. (G) Direction clutch pressure tap P2. (A) Oil pump output pressure tap (E) Speed clutch pressure tap P1 (G) Direction clutch pressure tap P2 | |
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| Illustration 3 | g00108012 |
992G Wheel Loader Transmission Control Valve (E) Speed clutch pressure tap P1 (G) Direction clutch pressure tap P2 (K) Plug for load piston LP | |
Note: The oil pump output pressure tap (A) is in the same location for both machines. Plug (K) for the load piston LP is in the same location for both machines.
- Engage the parking brake. Shift the STIC transmission direction control switch to the NEUTRAL position. Shift the transmission to first speed. Start the engine and operate the engine at low idle.
- Depress the right service brake pedal and hold the right service brake pedal. Release the parking brake. Watch the pressure gauges. Shift the STIC transmission direction control switch 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 5 clutch should rise. The pressure readings must be within the values that are found in Table 3.
With the transmission in the FORWARD position, shift through the remaining forward speeds and return to the FIRST SPEED position. The pressure reading for each clutch that is energized must be within the values that are found in Table 3. This checks the pressure of all the speed clutches.
- Perform Step 3 for all reverse speeds. The same pressure levels should be noted in all reverse speeds.
Test for the Lubrication Oil Pressure
Use the following procedure to check the pressure of the transmission lubrication oil.
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| Illustration 4 | g00108016 |
Input Transfer gear (J) Transmission lubrication pressure tap | |
- Install the correct hose assembly from 1U-5482 Pressure Adapter Group on pressure tap (J) . 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 .
- Start the engine and operate the engine at high idle. Observe the pressure gauge. With the oil at normal operating temperature, the lubrication oil pressure must be within values that are found in Table 3.
Transmission Pressures
| Transmission Pressure | ||||
| Pressure | Pressure Tap | Position of Governor Control Lever | Adjustment | |
| Pressure at Low Idle | Pressure at High Idle | |||
| Oil Pump | (A) | This pressure is identical to speed clutch pressure P1. | This pressure is identical to speed clutch pressure P1. | - |
| Speed Clutch P1 (Initial Pressure) | (E) | The pressure is 530 ± 35 kPa (77 ± 5 psi) when the direction switch is in the NEUTRAL position and plug (K) for the load piston is removed. |
- | Add spacers (34) or remove spacers (34) . |
| Speed Clutch P1 | (E) | This pressure must not be more than 480 kPa (70 psi) below the pressure at high idle. Plug (K) for the load piston is installed. |
This pressure is 2551 ± 140 kPa (365 ± 20 psi) when the direction switch is in FORWARD or in REVERSE and any speed is selected. Plug (K) for the load piston is installed. |
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| Direction Clutch P2 | (G) | This pressure is 380 ± 35 kPa (55 ± 5 psi) lower than the speed clutch pressure at pressure tap (E) . Plug (K) for the load piston is installed. |
This pressure is 380 ± 35 kPa (55 ± 5 psi) lower than the speed clutch pressure at pressure tap (E) . Plug (K) for the load piston is installed. |
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| Transmission Lubrication Oil | (J) | - | This pressure is approximately 172 ± 27 kPa (25 ± 4 psi). |
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Adjustments for the Transmission Pressures
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| Illustration 5 | g02699681 |
Transmission Selector and Pressure Control Valve (20) Load piston (34) Spacers | |
| Pressure Change for the Valve (1) | |||
| Description | Thickness | Pressure Change | Location of Spacers |
| 5M-9622 Spacer (34) | 1.58 mm (.062 inch) |
98 kPa (14.2 psi) |
Load Piston (20) |
| 5M-9623 Spacer (34) | 0.91 mm (.036 inch) |
57 kPa (8.20 psi) |
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| 5M-9624 Spacer (34) | 0.25 mm (.010 inch) |
16 kPa (2.29 psi) |
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| ( 1 ) | Result of the addition of one spacer or the removal of one spacer to the valve. |