| Required Tools | |
| Part Number | Description |
| 1U-5481 | Pressure Gauge Group |
| 6V-7788 | Flow Meter |
The pilot and braking pump is a vane pump. Measuring the oil flow can provide an indication of the condition of the pump. An inadequate amount of oil flow from the vane pump indicates that there is excessive internal leakage in the pump. This can be caused by wear or damage of the pump components. The pump flow should be measured at high idle and measured at low idle. Flow loss at low idle is more critical.
 |
Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth, level surface. Lower the work tool to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock. |
 |
|
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 work tools have been lowered to the ground, and the 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. |
|
| NOTICE |
|---|
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, "AVSpare Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on AVSpare products. Dispose of all fluids according to local regulations and mandates. |
Machine Preparation for Testing
Reference: For more information about preparing to test the pilot pump, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine system that is being serviced.
- Park the machine on a smooth, level surface. Move away from other operating machines and away from personnel. Lower the implements to the ground. Stop the engine.
- Move the steering frame lock to the locked position.
- Engage the parking brake.
- Release all hydraulic pressure before any fitting, any hose, or any component is loosened, tightened, removed, or adjusted.
Reference: For more information about releasing system hydraulic pressure, refer to the Service Manual module Testing and Adjusting, "System Pressure - Release" for the machine system that is being serviced.
- Move the transmission direction control switch to the NEUTRAL position. Turn the engine start switch key to the ON position.
- Depress the brake pedal repeatedly. This will relieve any pressure that may be present in the brake hydraulic system. In order to release all pressure in the brake accumulators, it may be necessary to pump the brakes 30 to 40 times.
- Move the implement control levers through the full range of travel. This will relieve any pressure that may be present in the implement hydraulic system.
- Turn the steering wheel several times in both directions in order to relieve the pressure in the steering system.
- Push in the plunger on the hydraulic tank breaker relief valve in order to relieve the pressure in the hydraulic oil tank.
- Disconnect the implement pilot supply line (1) from the main control valve. The main control valve is located in the non-engine end frame of the machine. Close off the implement pilot supply line in order to accurately measure the flow from the pilot/brake pump.
 | |
| Illustration 1 | g00834992 |
- Disconnect the hose from the inlet (2) of the brake accumulator charging valve (3). Install a tee connection and a 1U-5481 Pressure Gauge Group in order to measure the discharge pressure of the pilot/brake pump.
 | |
| Illustration 2 | g00835023 |
- Install the 6V-7788 Flow Meter between the inlet line (2) and the brake accumulator charging valve (3) .
Reference: For more information about using a 6V-7788 Flow Meter, refer to the Special Instruction, "SMHS8284".
Testing Procedure
- Start the engine. Warm the hydraulic oil to normal operating temperature of approximately 65°C (150°F).
- Run the machine at high idle. Set the engine speed at 2100 rpm. If the machine is not equipped with a throttle lock control, use the governor pedal to set the engine speed.
- Record the oil flow when the brake accumulators are fully charged and the pump pressure drops to the standby pressure of 4310 ± 210 kPa (625 ± 30 psi).
- If the oil flow at high idle is less than 39.5 L/min (10 US gpm), the pilot/brake pump needs to be repaired or replaced.
- Run the machine at low idle. Set the engine speed at 1050 rpm. If the machine is not equipped with a throttle lock control, use the governor pedal to set the engine speed.
- Record the oil flow when the brake accumulators are fully charged and the pump pressure drops to the standby pressure of 4310 ± 210 kPa (625 ± 30 psi).
- If the oil flow at low idle is less than 19.8 L/min (5 US gpm), the pilot/brake pump needs to be repaired or replaced.
- Stop the engine.
- Repeat steps 4 through step 9 of "Machine Preparation for Testing".
- Remove the test equipment. Connect the inlet hose of the pilot/brake pump to the brake accumulator charging valve. Connect the implement pilot supply line to the main control valve.