LINK AS.-TRACK 3305418 - Caterpillar

At operating temperature, the hydraulic oil is hot and under pressure. Hot oil can cause burns. Sudden movement of the machine or release of oil pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the following procedure before working on the hydraulic and steering systems.
a. Move the machine to a smooth horizontal location. Move away from working machines and personnel. Lower all implements to the ground. Install the wheel lean pin in front axle.b. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.c. Activate the parking brake. Place all implements on the ground and put the blade in the "FLOAT" position.d. Stop the engine.e. Turn the steering wheel back and forth several times to relieve pressure in the steering accumulator.f. Carefully loosen the filler cap on the hydraulic tank to release pressure in the tank.g. Be sure all hydraulic pressure is released before any fitting, hose, or component is loosened, tightened, removed or adjusted.h. Tighten the cap on the hydraulic tank.i. The pressure in the hydraulic system must be released before lines or components can be removed.
Hydraulic pressure can exist in the hydraulic lines between the control valves and the cylinders with the engine stopped. Manually relieve pressure before working on any hydraulic circuit.
2. Remove plug (1) from ecology drain (2) at the bottom of the hydraulic oil tank. Drain the hydraulic oil in a suitable container for storage or disposal. The capacity of the hydraulic oil tank is 63 liters (17 U.S. gal). Do not release the nitrogen from the steering hydraulic accumulator unless the unit is to be disassembled.3. Loosen locknut (4) at the base of hydraulic accumulator (3). Remove steering hydraulic accumulator (3) from the combination valve. Remove the O-ring from steering hydraulic accumulator (3).Install Steering Hydraulic Accumulator
1. Prior to installing steering hydraulic accumulator (3), check the condition of the O-ring seal used in accumulator (3). If the seal is damaged, use new parts for replacement. 2. Install the O-ring seal in steering hydraulic accumulator (3). Install steering hydraulic accumulator (3) in the combination valve. Tighten locknut (4). 3. Close ecology drain (2), and install plug (1). Fill the hydraulic oil tank with oil to the correct level. Refer to the "Operation & Maintenance Manual" for the correct procedure.4. Check and charge steering hydraulic accumulator (3). Refer to the "Operation & Maintenance Manual" for the correct "Steering Hydraulic Accumulator Pressure and Precharge Check."