COVER B91761701 - Caterpillar

Illustration 2 g01236270
Location of the Components for the Grapple (4) Boom cylinders (5) Arch cylinders (6) Tong cylinders (8) Rotator (13) Boom control valve (14) Arch control valve (15) Tong control valve (16) Rotator control valve (18) Pilot valve (20) Accumulator (Pilot oil) (27) Pressure reducing valveNote: The 525C Wheel Skidder can be equipped with a three bank valve group. The valve group consists of a tong valve, a rotator valve, and a boom valve.
Illustration 3 g01211562
(28) Tong CLOSE (29) Grapple ROTATE COUNTERCLOCKWISE (30) Tong OPEN (31) Grapple ROTATE CLOCKWISE (32) Grapple control lever (33) Tong auto/manual switchBoom control valve (13) , arch control valve (14) , tong control valve (15) and rotator control valve (16) are all part of the main control valve. These valves are located on the rear of the machine. The arch and the boom valves are pilot operated. Pilot valve (18) directs low pressure oil to the control valves. The pilot valve is operated by grapple control lever (32) . The pilot valve is located at the rear of the cab on the right side of the machine.The pilot system uses low pressure oil to operate boom control valve (13) and arch control valve (14) . The main components of the pilot system include hydraulic tank (26) , hydraulic pump (24) , pressure reducing valve (27) , accumulator (20) , and pilot valve (18) .When the engine is activated, the oil from hydraulic tank (26) flows to the pilot pump on hydraulic pump assembly (24) . From the hydraulic pump, the oil flows to the pilot manifold. The pressure reducing valve on the pilot manifold limits the pilot system pressure to 2585 140 kPa (375 20 psi). The oil charges accumulator (20) . The oil then flows to pilot valve (18) . Boom control valve (13) and arch control valve (14) are closed center valves that have three positions. The arch control valve includes IN, HOLD, and OUT positions. The boom control valve includes UP, HOLD, and DOWN positions.Oil will not flow through either of the closed center valves when the valve is in the HOLD position. Oil lines connect the output of pilot valve (18) to the pilot inlet ports on boom control valve (13) and arch control valve (14) .When control lever (32) is moved to the UP