PIN AS 4165465 - Caterpillar

Pilot Hydraulic System
The pilot hydraulic oil is supplied to the pilot system from the main hydraulic pump. The main hydraulic pump is driven by the engine. Oil flow from the main pump is directed into the main control valve and through the pump outlet passage to the pilot manifold. Oil then flows to an inline oil filter and a pressure reducing valve. The inline oil filter is where the oil is filtered and the pressure reducing valve sets the pilot oil circuit pressure. From the pressure reducing valve the pilot pressure oil is always made available to the operator joysticks and travel lever/pedals. Pilot oil is also supplied to various other components.When the hydraulic lockout lever in the operator compartment is in the LOCKED position, pilot oil is blocked. When the hydraulic lockout lever is in the UNLOCKED position, pilot pressure oil is sent to the operator controls, enabling implement operation and travel.The pilot manifold contains a number of subcomponents that will be discussed in greater detail in this manual. The pilot hydraulic system is divided into three basic circuits that utilize pilot pressure oil for the following functions:
Pilot control valves for implement and travel operation
Two-speed travel operation to destroke the travel motors for high speed travel
Swing brake operation to release the swing brake during implement operationNote: Refer to the appropriate sections in this manual for more information.