CYLINDER HEAD GP 1985855 - Caterpillar

Illustration 1 g03795275
(1) Hydrostatic pump (2) Pilot shut off / Differential lock manifold (3) Implement pump (4) Implement valve (5) Tilt pilot solenoids (6) Pilot spool (7) Pilot relief valves (8) Tilt cylinder (9) Hydraulic tankThe control valves for the auxiliary, lift, and tilt operation of the bucket, are all part of Implement Valve (4). All the sections of the implement valve work identically. All of the control valves are pilot operated. Oil flows from the implement section of pump (3) to the implement valve. Each control valve directs the flow of oil to a specific circuit. The pilot solenoids are electrohydraulic and activated by a controller in the operator station. The tilt controller is attached to the tilt pilot solenoids (5). When the controller is moved, the controller causes the tilt control solenoids to send pilot oil to the main control valve spool for tilt (6). The main control spool for tilt (6) routes implement oil from pump (3) to either the rod end or head end of tilt cylinder (8) to perform work.The lift controller is attached to the lift pilot solenoids. When the controller is moved, the controller causes the lift control solenoids to send pilot oil to the main control spool for lift. The main control spool for lift routes oil from implement pump (3) to either the rod end or head end of lift cylinders to perform work.The auxiliary controller is attached to the auxiliary valve. When the lever is moved, the lever causes the auxiliary control solenoids to send pilot oil to the main control spool for auxiliary attachments. The auxiliary control spool routes implement oil from pump (3) to either the rod or head ends of auxiliary cylinders through lines to perform work.Relief valves (7) that are in the main control valve for tilt maintain the hydraulic system pressure for tilt circuit. Both the lift and auxiliary circuits also contain relief valves that maintain the hydraulic system pressure. Refer to Specifications, "Implement Valve" for the system pressure settings of the relief valves. The relief valves also reduce the possibility of damage to the circuit components when the main control valves are actuated. Relief valves in the auxiliary and main control valve for tilt, maintain the circuit pressure when in the HOLD position.A manual activated valve is used in order to lower the loader assembly when the engine is dead. The manual valve drains oil from the head end of the lift cylinder back to tank (9) and lowers the loader assembly to the ground. When you actuate a control valve, main relief valve maintains implement system pressure. At the same time, the main relief valve reduces the possibility of damage to the circuit components. When the oil pressure in the line from pump (3) reaches 23500 kPa (3407 psi), the relief valve opens. Oil in the line from pump (3) flows back into the tank orifice that is in the implement valve. Then, the oil flows to tank (9).