The following procedure is used in order to test the Transmission Hydrostatic Actuation.
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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand. |
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When testing and adjusting the transmission and power train, move the machine to an area clear of obstructions, with safe exhaust ventilation for the exhausts. Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before testing and adjusting the transmission and power train. |
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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. |
- Move the machine to a smooth horizontal location. Move away from working machines and personnel. Lower the work tools to the ground.
- Allow only one operator on the machine. Keep all personnel away from the machine or in the view of the operator.
- Engage the parking brake.
- Place the steering frame lock in the LOCKED position.
Reference: For more information about preparing the machine for troubleshooting, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Testing and Adjusting" for the machine that is being serviced.
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| Illustration 1 | g01089423 |
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| Illustration 2 | g01623868 |
| Tool | Item | Part Number | Description | Qty |
|---|---|---|---|---|
| A | A1 | 8T-0856 | Pressure Gauge
(0 to 6,000 kPa (0 to 870 psi)) |
1 |
| A2 | 6V-3989 | Fitting | 1 | |
| A3 | 6V-4143 | Quick Connect Coupler | 2 | |
| A4 | 177-7860 | Hose As
(3.0 m (10 ft)) |
1 | |
| B | 198-4240 | Digital Pressure Indicator Gp | ||
| B1 | 198-4234 | Digital Indicator | 1 | |
| B2 | 198-4238 | Pressure Sensor Gp
(0 to 3,440 kPa (0 to 5000 psi)) |
1 | |
| B3 | 198-4236 | Adapter Cable As | 1 | |
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| Illustration 3 | g03784882 |
(1) Transmission hydrostatic pump pressure - Actuator (A)
(2) Transmission hydrostatic pump pressure - Actuator (B)
(3) Transmission charge pump pressure
Transmission Hydrostatic Actuation Pressures
| 966/ 972 | ||||||
| Valve A-OFF
Valve B-OFF |
Valve A-ON
Valve B-OFF |
Valve A-OFF
Valve B-ON |
Valve A-ON
Valve B-ON |
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| Pump A
Pressure |
kPa/psi | |
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| Pump B
Pressure |
kPa/psi | |
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| Charge
Pressure |
kPa/psi | |
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| Transmission
Lube Pressure |
kPa/psi | |
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| Loop A
Pressure |
kPa/psi | |
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| Loop B
Pressure |
kPa/psi | |
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| Motor Speed Ratio | N/A | 0 ±0.1 | -1.35 ±0.15 | 1.35 ±0.15 | 0 ±0.1 | |
| Hydrostatic Out
Oil Temperature |
° C (° F) | |
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Transmission Hydrostatic Actuation Test
Use the following for the Transmission Hydrostatic Actuation Test
Perform the steps in the "Machine Set Up" and then continue to the following steps.
- Select Transmission Hydrostatic Actuation Test.
Show/hide table
Illustration 5 g03695959 - Set up conditions are met, click the "Next>" button to continue
Set up calibration conditions:
- Before starting the engine, connect a gauge to the hydrostatic pump pressure ports and to the transmission charge pressure port.
- Warm Transmission Hydrostatic Outlet Oil Temperature to
70° C (158° F) or higher. - Move the direction switch to the neutral position.
- Apply the Parking Brake.
- Fully release the brake pedal.
Show/hide table
Illustration 6 g03695961 - Both pump valves are off
Hydrostatic pump solenoid # 1 is set to 0% current. Hydrostatic pump solenoid #2 is set to 0% current.
- Record both hydrostatic pump pressures, both loop pressures, the charge pressure, the hydrostatic speed ratio, and the hydrostatic outlet oil temp.
- Record the specified values and then click and Next> button to continue.
Show/hide table
Illustration 7 g03695962 - Running Pump Valve #1 Pressure Sweep. ... ... ...
Hydrostatic pump solenoid # 1 is set to 100% current. Hydrostatic pump solenoid #2 is set to 0% current.
- Record both hydrostatic pump pressures, both loop pressures, the charge pressure, the hydrostatic speed ratio, and the hydrostatic outlet oil temp.
- Record the specified values and then click and Next> button to continue.
Show/hide table
Illustration 8 g03695964 - Running Pump Valve #2 Pressure Sweep. ... ... ...
Hydrostatic pump solenoid # 1 is set to 0% current. Hydrostatic pump solenoid #2 is set to 100% current.
- Record both hydrostatic pump pressures, both loop pressures, the charge pressure, the hydrostatic speed ratio, and the hydrostatic outlet oil temp.
- Record the specified values and then click and Next> button to continue.
Show/hide table
Illustration 9 g03695966 - Running Pump Valve #1 and Pump Valve #2 Pressure Sweep tests. ... ... ...
Hydrostatic pump solenoid # 1 is set to 100% current. Hydrostatic pump solenoid #2 is set to 100% current.
- Record both hydrostatic pump pressures, both loop pressures, the charge pressure, the hydrostatic speed ratio, and the hydrostatic outlet oil temp.
- Record the specified values and then click and Next> button to continue.
Show/hide table
Illustration 10 g03695956 - Service Test Successful
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| Illustration 4 | g03695965 |
