Hot hydraulic oil under high pressure can remain in the components of the hydraulic system or the power train system after the engine has been stopped. The uncontrolled release of the hydraulic oil can cause sudden machine movement and can also result in the following conditions:
If hydraulic oil penetrates body tissue, the injury must be treated immediately by a doctor who is familiar with this type of injury. Use a board or a piece of cardboard to check for a hydraulic oil leak. Make sure that all of the attachments have been lowered to the ground and that all trapped pressure has been released from the hydraulic system and the power train system. Also, make sure that the hydraulic oil is cool before the removal of any components or lines. Remove the hydraulic oil filler cap only when the engine is stopped and the filler cap is cool enough to touch with your bare hand.
Personal injury or death can result from not engaging the parking brake.
Transmission engagement alone will not prevent machine from rolling when the engine is stopped.
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.
|Case Pressure (Steering Pump)|
|Date||Equipment ID Code|
|Case Pressure at HIGH IDLE at Pressure Tap (R)||
During normal operation, a small amount of oil leaks into the cases of the steering pump and the steering motor. Check the case pressure in order to ensure that the leaking oil is draining properly out of the case. High case pressure could indicate a clogged drain line.
Tooling (A) 198-4240 Digital Pressure Indicator Gp|
|A||198-4240||Digital Pressure Indicator Gp|
|A2||1||198-4237|| Pressure Sensor Gp
(0 to 3,445 kPa (0 to 500 psi))
|A3||1||198-4236||Adapter Cable As|
Reference: Refer to Tool Operating Manual, NEHS0818, "Using the 198-4240 Digital Pressure Indicator Group" for more information on using tooling (B).
- Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.
- Permit only one operator on the machine. Keep all other personnel away from the machine or in the sight of the operator.
- Place the steering control lever in the NEUTRAL position.
- Engage the parking brake.
- Lower the attachments to the ground.
- Stop the engine.
- Turn the key to the ON position, but do not start the engine.
- Verify that the implement shutoff control is in the UNLOCKED position.
- Move the implement control levers and the transmission control lever through the full range of travel several times. This movement will relieve any pressure that may be present in the implement hydraulic system and the power train system.
- Loosen the filler cap on the hydraulic tank so that the pressure in the tank is released. The machine may be equipped with a breaker valve. The breaker valve will be located on top of the tank. To release the pressure in the tank, press the button on top of the breaker valve.
- Tighten the filler cap on the hydraulic tank.
- Make sure that the pressure in the entire hydraulic system has been released.
Reference: For additional guidance with preparing the machine for testing, refer to the Testing and Adjusting manual or the Troubleshooting manual for your machine.
Note: The monitoring system (if equipped) for your machine accesses many values that are useful in troubleshooting the hydraulic system. When the situation is appropriate, use the monitoring system in order to find a pressure or determine a system problem.
- Open the access panel on the right side of the machine.
Illustration 2 g03714415 (R) Pressure tap for the steering pump case
- Attach tooling (A) to pressure tap (R).
- Perform steps in "Check Preparation".
- Start the engine and operate the engine at HIGH IDLE.
- Warm the hydraulic oil to
55° ± 10°C (131° ± 18°F).
- The reading on the gauge should be
40 ± 25 kPa (6 ± 4 psi).
- If the reading is not within specifications, check that there is no obstruction in the case drain line to the tank.
- If, the reading exceeds
100 kPa (15 psi)check the case drain filter.
- Stop the engine and remove tooling (A).