 |
|
Hydraulic oil pressure can remain in the hydraulic system on this machine after the engine and pump have been stopped. Serious injury can result if this pressure is not released before any service is done on the hydraulic system. In order to prevent possible injury, release the hydraulic system pressure before working on any fitting, hose, or hydraulic component. Lower all work tools to the ground before service is started. If the hydraulic system must be serviced, tested, or adjusted with the work tool in the raised position, the work tool and lift cylinders must be supported properly. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made. |
| NOTICE |
|---|
|
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids. Dispose of all fluids according to local regulations and mandates. |
| Load Sense Pressure | ||
|---|---|---|
| Description | Specification | Actual |
| Pressure reading at 800 rpm low idle | |
|
| Pressure reading at 2150 rpm high idle | |
|
| Margin Pressure | ||
|---|---|---|
| Description | Specification | Actual |
| Pressure reading at 2000 rpm engine speed | |
|
| Main Pump Discharge Pressure | ||
|---|---|---|
| Description | Specification | Actual |
| Pressure reading at 800 rpm low idle | |
|
| Pressure reading at 2150 rpm high idle | |
|
| Steering Signal Relief Pressure | ||
|---|---|---|
| Description | Specification | Actual |
| Pressure reading at 800 rpm low idle | |
|
Reference: Refer to Operation and Maintenance Manual, "Prepare the Machine for Maintenance" and "System Pressure Release".
The following procedure will explain the steps to test and adjust the pump controller and combination valve. Perform all procedures, in sequence.
| |
| Illustration 1 | g02118318 |
|
Tooling (A) | |
| |
| Illustration 2 | g01623868 |
|
Tooling (B) | |
| Tool | Item | Part Number | Description | Qty |
| A | A1 | 8T-0855 | Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)) | 1 |
| A2 | 8T-0858 | Pressure Gauge (0 to 16,000 kPa (0 to 2,300 psi)) | 1 | |
| A3 | 8T-0859 | Pressure Gauge (0 to 25,000 kPa (0 to 3,600 psi)) | 1 | |
| A4 | 6V-3989 | Fitting | 1 | |
| A5 | 6V-4143 | Quick Connect Coupler | 2 | |
| A6 | 177-7862 | Hose As (5.5 m (18 ft)) | 1 | |
| B | 198-4240 | Digital Pressure Indicator Gp | 1 | |
| 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 | |
| D | 1U-7563 | Hex Wrench | 1 | |
| F | 1U-5796 | Pressure Differential Tool Gp | ||
| F1 | 177-7861 | Hose As | 2 | |
| F2 | 6V-4143 | Quick Connect Coupler | 4 | |
| F3 | 6V-3965 | Fitting | 3 | |
| F4 | 6V-4144 | Quick Connect Coupler | 1 | |
| F5 | 8T-0859 | Pressure Gauge
(0 to 25,000 kPa (0 to 3,600 psi)) |
1 | |
| F5 | 8T-0861 | Pressure Gauge
(0 to 60,000 kPa (0 to 8,700 psi)) |
1 | |
| F6 | 8C-8431 | Tee | 1 | |
| F7 | 1U-5793 | Oil Filter Pressure Differential Gauge Gp | 1 | |
| F8 | 6V-0484 | O-Ring Adapter | 1 | |
Note: Tooling (A) or Tooling (B) may be used to perform these tests.
- Move the machine to a smooth horizontal location.
- Chock the wheels.
- Lower all of the implements.
- Start the engine.
- Operate the engine at low idle. Operate the implement controls for 3 minutes to 10 minutes in order to raise the hydraulic oil temperature to normal operating temperature range.
- Stop the engine.
Show/hide table
Illustration 3 g06377636 View of pump discharge pressure port and load sense pressure port.
(10) Pressure test port for pump discharge pressure
(18) Pressure test port for implement load sense pressure - Remove the dust cover from test port (10).
Note: The combination valve and the pump control valve are accessible from the ground. The valves are located under the cab platform and on the left side of the machine. These components are near the rear cab support.
- Remove the dust cover from load sense pressure test port (18).
Note: The blade lift control must be in the neutral position before engine start-up. Test equipment will be damaged if the blade control valve is in the float position at engine start-up. The machine may be equipped with a hydraulic detent. The blade control valve should move from the float position to the neutral position when the engine is shut off.
- Check in order to ensure that the blade lift controls are in the neutral position.
- Attach Tooling (A) or (B) to main pump discharge pressure port (10). Use a gauge suitable for the specified pressure.
- Attach Tooling (A) or (B) to load sense pressure port (18). Use a gauge suitable for the specified pressure.
Load Sense Pressure - Test and Adjust
| |
| Illustration 4 | g01726974 |
|
Side view of the combination valve (1) Pressure switch port (2) Supply port for the valve group (3) Supply port for the valve group (4) Steering signal (5) Steering relief valve (6) Implement signal relief valve (7) Pump signal (8) Signal purge valve (9) Control valve signal (10) Pressure test port for pump discharge pressure (11) Auxiliary return port (12) Main pump relief valve (13) Valve group return port (14) Hydraulic tank return port (15) Steering supply port (16) Secondary steering pump port | |
- Start the engine.
- Operate the engine at 800 rpm low idle.
- Stall the blade tip cylinder. While the blade tip cylinder is stalled, record Load Sense pressure from the gauge at test port (18).
The pressure should read
22050 ± 300 kPa (3200 ± 44 psi) . - Raise engine speed to 2150 rpm high idle.
- Stall the blade tip cylinder. While the blade tip cylinder is stalled, record Load Sense pressure from the gauge at test port (18).
The pressure should read
22050 ± 300 kPa (3200 ± 44 psi) . - Stop the engine.
- If necessary, adjust Load Sense pressure at Implement Signal Relief Valve (6) on the combination valve.
Loosen the locknut and hold the locknut still while turning the adjustment screw.
Turn the adjustment screw counterclockwise to reduce pressure.
Turn the adjustment screw clockwise to increase pressure.
Hold the adjustment screw still and tighten the locknut.
- Repeat the testing and adjusting procedure until the pressure reading is correct.
Note: If Load Sense Pressure is too low and unable to be adjusted to specification, refer to Testing and Adjusting , "Relief Valves (Implement) - Test and Adjust" to verify main pump discharge pressure relief valve operation.
Flow Compensator (Margin Pressure) - Test and Adjust
Note: Before you perform this adjustment, refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".
| |
| Illustration 5 | g06377638 |
|
Pressure and flow compensator valve (19) Adjustment screw for the flow compensator (margin pressure) (20) Locknuts (21) Adjustment screw for the pressure compensator (pressure cutoff) | |
- Operate the engine at 2000 rpm high idle.
- Operate the circle drive and rotate the blade at full speed.
- While the circle is in motion, record the pressures from the gauges connected to Pump Discharge Pressure Port (10) and Load Sense Pressure Port (18).
- Subtract Load Sense Pressure reading from Pump Discharge Pressure reading. The difference between the two pressures is Margin Pressure. The pressure difference should be
2100 ± 100 kPa (305 ± 15 psi) .Note: This is a differential pressure measurement. Be sure to use gauges rated for the individual port pressure specifications.
- Stop the engine.
- If necessary, adjust Load Sense pressure at pump controller Adjustment Screw (19).
Loosen Locknut (20) and hold the Locknut still while turning Adjustment Screw (19).
Turn Adjustment Screw (19) counterclockwise to reduce pressure.
Turn Adjustment Screw (19) clockwise to increase pressure.
Hold the Adjustment Screw still and tighten Locknut (20).
- Repeat the testing and adjusting procedure until the pressure reading is correct.
Pump Main Discharge Pressure - Test
- Start the engine. Operate the engine at 800 rpm low idle.
- Stall the blade tip cylinder. While the blade tip cylinder is stalled, record Main Pump Discharge pressure from the gauge at test port (10).
The pressure should read
24150 + 400 / - 1035 kPa (3503 + 58 / - 150 psi) . - Raise engine speed to 2150 rpm high idle.
- Stall the blade tip cylinder. While the blade tip cylinder is stalled, record Main Pump Discharge pressure from the gauge at test port (10).
The pressure should read
24150 + 400 / - 1035 kPa (3503 + 58 / - 150 psi) . - Stop the engine.
- If the main pump discharge pressure reading is incorrect, repeat the procedures for "Load Sense Pressure - Test and Adjust" and "Flow Compensator (Margin Pressure) - Test and Adjust" until the main pump discharge pressure is correct.
Steering Signal Relief Pressure - Test and Adjust
|
| |
| Illustration 6 | g01726974 |
|
Side view of the combination valve (1) Pressure switch port (2) Supply port for the valve group (3) Supply port for the valve group (4) Steering signal (5) Steering relief valve (6) Implement signal relief valve (7) Pump signal (8) Signal purge valve (9) Control valve signal (10) Pressure test port for pump discharge pressure (11) Auxiliary return port (12) Main pump relief valve (13) Valve group return port (14) Hydraulic tank return port (15) Steering supply port (16) Secondary steering pump port | |
- Start the engine. Operate the engine at 800 rpm low idle.
- Steer full left to stall the steering cylinder. While the steering cylinder is stalled, record Load Sense pressure from the gauge at test port (18).
The pressure should read
17400 ± 300 kPa (2524 ± 44 psi) . - Stop the engine.
- If necessary, adjust Steering Signal Relief at Combination Valve Steering Relief Valve (5).
Loosen the and hold the locknut still while turning the adjustment screw.
Turn the adjustment screw counterclockwise to reduce pressure.
Turn the adjustment screw clockwise to increase pressure.
Hold the adjustment screw still and tighten the locknut.
- Repeat the testing and adjusting procedure until the pressure reading is correct.