 |
Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak. |
 |
| 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 in Caterpillar machines. Dispose of all fluids according to local regulations and mandates. |
Note: The oil in the hydraulic system must be at an operating temperature of 50° ± 5°C (122° ± 9°F). This temperature range is specified for standard factory fill oil only. Use the Electronic Technician Software in order to monitor this temperature. Or refer to Testing and Adjusting, "Hydraulic Oil Temperature Test" for an alternate procedure.
Specifications
| Pilot system Pressure Specifications (All Models) | ||
| Description | Specification | Actual |
| Charge Pressure (Low Idle) | 2750 ± 200 kPa (399 ± 29 psi) |
|
| Charge Pressure (High Idle) | 3100 ± 200 kPa (450 ± 30 psi) |
|
| Pilot Pressure for Work Tool (Low Idle) | 2750 ± 200 kPa (399 ± 30 psi) |
|
| Pilot Pressure for Work Tool (high Idle | 3100 ± 200 kPa (450 ± 30 psi) |
|
Introduction
The pilot system pressure test determines the pilot control pressure to the electrohydraulic controls. The pilot oil is supplied by the charge pump section of the gear pump. This test is performed in order to determine if the control pressure that is supplied to the work tool control valve is within the specification.
Required Tools
| Required Tools | ||||
|---|---|---|---|---|
| Tool | Item | Qty | Part No | Description |
| A | 198-4240 | Digital Pressure Indicator Gp | ||
| A | A1 | 1 | 198-4234 | Digital Indicator |
| A2 | 1 | 198-4239 | Pressure Sensor Gp (0 to 41,368 kPa (0 to 6,000 psi)) |
|
| A3 | 1 | 198-4236 | Adapter Cable As | |
| B | B1 | 1 | 8T-0855 | Pressure Gauge (0 TO 4,000-KPA (0 TO 580-PSI)) |
| B2 | 1 | 6V-3989 | Fitting | |
| B3 | 2 | 6V-4143 | Quick Connect Coupler | |
| B4 | 1 | 177-7861 | Hose As (4.3 M (14 FT)) | |
| F | F1 | 1 | 6V-3965 | Fitting (TEST) |
| F2 | 1 | 7X-2444 | Swivel Tee | |
| F3 | 1 | 6V-5049 | O-Ring Seal | |
| F4 | 1 | 3J-1907 | O-Ring Seal | |
Test Preparation
Before any tests are performed, visually inspect the complete hydraulic system for oil leaks and damaged parts. Refer to Testing and Adjusting, "Visual Inspection". Before any tests are performed, prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".
Test Procedure
- Engage the parking brake. Stop the engine.
- Block the tracks/tires of the machine.
- Release the hydraulic pressure. Refer to Testing and Adjusting, "System Pressure - Release" for the proper procedure.
- Raise the cab. refer to Operation and Maintenance Manual, "Cab Tilting" for tilting procedure.
- Install one Tooling B1 to the charge pressure test port (1) with one Tooling B4.
| Illustration 1 | g03381764 |
- Install one Tooling B1 to the work tool system pressure test port (2) with one Tooling B4.
| Illustration 2 | g03380787 |
| Illustration 3 | g03410716 |
- Secure the two hydraulic lines so that the pressure gauges can be viewed by the operator during the test. The hoses should not be pinched when the cab is lowered.
- Lower the cab.
- Sit in the operator seat. Fasten the seat belt and lower the armrest.
- Start the engine. Disengage the parking brake.
- Run the engine at LOW idle. Record the charge pressure and the pilot pressure.
- Run the engine at HIGH idle. Record the charge pressure and the pilot pressure. If the pilot pressure is not within specifications, refer to Testing and Adjusting, "Hydrostatic System - Test and Adjust".
Note: If no pilot pressure is recorded, the pilot shut off valve for the work tool may not be functioning correctly.
- Reduce the engine to LOW idle. Stop the engine.
- Release the hydraulic pressure. Refer to Testing and Adjusting, "System Pressure - Release" for the proper procedure.
- Raise the cab. Remove the test equipment.
- Lower the cab.
- Remove the track/wheel blocks.
