 |
Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause 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 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. |
Specifications
| Accumulator Specifications | ||
| Description | Specification | Actual |
| Pilot oil accumulator pressure | 3100 ± 200 kPa (450 ± 30 psi) |
|
Introduction
This procedure describes the method for checking the pilot oil accumulator pressure.
The following procedure can be used in order to test the pilot oil accumulator. The pilot oil accumulator maintains pressure in the pilot hydraulic system.
When you test or you charge the pilot oil accumulator, the pressure in the pilot hydraulic system must be released. The temperature of the nitrogen gas must also be taken into account. The pressure and volume of nitrogen gas varies with temperature.
Required Tools
| Illustration 1 | g02571852 |
| Illustration 2 | g02726620 |
| 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-0856 | Pressure Gauge (0 TO 6,000-KPA (0 TO 970-PSI)) |
| B2 | 1 | 6V-3989 | Fitting | |
| B3 | 2 | 6V-4143 | Quick Connect Coupler | |
| B4 | 1 | 177-7860 | Hose As 3.0 m (10 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
Accumulator Test
| Illustration 3 | g01349091 |
Typical accumulator that is not rechargeable | |
| Illustration 4 | g01349097 |
Typical rechargeable accumulator | |
Perform this test if the pilot accumulator is not rechargeable.
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".
- Move the machine to a smooth, horizontal location. Move the machine away from other operating machines and away from personnel.
- Lower the work tool to the ground. Stop the engine.
- Engage the parking brake.
- Block the tracks or wheels of the machine.
- Turn the engine start switch key to the ON position.
- Move the pilot valves to all positions in order to release the pressure in the hydraulic system.
- Turn the engine start switch key to the OFF position.
- Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation".
- Assemble Tooling F.
- Install Tooling F in line with pilot supply hose (4) and the pilot port (3).
| Illustration 5 | g03385411 |
The work tool control valve (1) and the accumulator (2) are located in the center of the machine. (1) Supply line for the pilot operated hydraulic control (work tool) (2) Accumulator (3) Location of the pilot port. (4) Pilot supply hose | |
- Assemble Tooling B and attach to Tooling F.
- Lower the cab. Do not pinch the hose.
- Sit in the seat. Fasten the seat belt and lower the armrest.
- Start the engine. Disengage the parking brake.
- Run the engine at HIGH idle. The pilot pressure should rise to 3100 ± 200 kPa (450 ± 30 psi). If the pilot pressure is not correct, refer to Testing and Adjusting, "Hydrostatic System - Test and Adjust".
- Use the hydraulic implement control in order to move the lift arms to the full RAISE position. Stop the engine.
- Turn the engine start switch key to the ON position.
- Use the hydraulic implement control in order to move the lift arms to the full LOWER position. The lift arms will lower. The pressure will decrease in one of the following ways:
- The pressure decreases slowly until the pressure reaches 900 ± 100 kPa (130 ± 15 psi). Then, the pressure decreases rapidly. If this pressure decrease happens, the accumulator is properly charged. Proceed to Step 19.
- If the pressure decreases rapidly the accumulator is not properly charged. Ensure that the check valve in the travel pilot ON/OFF solenoid valve is seated properly and repeat the procedure before replacing the accumulator. Refer to Disassembly and Assembly, "Accumulator - Remove and Install". Proceed to the Accumulator Charge.
- The pressure decreases slowly until the pressure reaches 900 ± 100 kPa (130 ± 15 psi). Then, the pressure decreases rapidly. If this pressure decrease happens, the accumulator is properly charged. Proceed to Step 19.
- Remove the block.
Accumulator Charge
The following procedure is performed in order to charge the rechargeable accumulator (pilot) to the correct precharge pressure.
|
Dry nitrogen is the only gas approved for use in the accumulators. The charging of oxygen gas in an accumulator will cause an explosion. An explosion can be eliminated by using nitrogen gas cylinders with standard CGA (Compressed Gas Association, Inc.) No. 580 connectors. When nitrogen gas is ordered, make sure to order the cylinders with CGA No. 580 connectors. Do not rely on color codes or other methods of identification to tell the difference between nitrogen and oxygen cylinders. In any application, never use an adapter to connect your nitrogen charging group to a valve outlet used on both nitrogen, oxygen, or other gas cylinders. BE SURE YOU USE DRY NITROGEN (99.8% purity). |
|
|
Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause 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 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. |
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".
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the proper procedure and Tooling required To perform the charging procedure.
