SWITCH AS-ROCKER 3990373 - Caterpillar

At operating temperature, the hydraulic oil tank is hot and under pressure. Hot oil can cause burns. To prevent possible personal injury, release the pressure in the implement hydraulic circuits (the boom, the stick and the bucket) before any of the hydraulic lines or any of the components are disconnected or removed.
2. Release the pressure in the implement hydraulic circuits (the boom, the stick and the bucket) before any of the hydraulic lines or any of the components are disconnected or removed. Release the pressure as follows:a. Shut off the engine and place key in the "ON" position. Put the hydraulic activation control lever in the "UNLOCK" position.b. Move the control levers for the boom, the stick and the swing to all full stroke positions. This will release any pressure that might be present in the pilot system.c. Return the key to "OFF" position.d. Slowly loosen the fill plug on the hydraulic tank, and release the pressure.e. Tighten the fill plug on the hydraulic tank.f. The pressure in the hydraulic system has been released, the lines and the components can be removed. 3. Remove five bolts (1), the washers and cover plate (2) from under the cab.
View From Under Cab4. Put identification marks on four hose assemblies (3) for installation purposes.5. Oil will drain from four hose assemblies (3) and the