VALVE GP-PILOT 1870521 - Caterpillar

Illustration 1 g00280656
Cushion-Hitch Piston Pump (1) Pressure compensator valve. (2) Control piston. (3) Pump shaft. (4) Pump outlet. (5) Pump inlet. (6) Rotating group. (7) Swashplate. The cushion-hitch piston pump is an axial, piston type pump. This type of pump is also called a swashplate pump. On the 621F and on the 627F Wheel Tractor-Scrapers, the cushion-hitch piston pump is attached to the rear of the transfer case.On the 623F Wheel Tractor-Scraper, the cushion-hitch piston pump is attached to the rear of the elevator pump. This elevator pump is attached to the rear of the transfer case.While the engine is running, pump shaft (3) rotates. Rotating group (6) is driven by pump shaft (3) .Cushion-hitch pump has nine pumping pistons. The pumping pistons alternately suction hydraulic oil from the hydraulic oil tank and through pump inlet (5). The pumping pistons push the hydraulic oil through pump outlet (4). The majority of this hydraulic oil is pumped into the hydraulic system of the cushion-hitch.The pumping pistons are connected to a retraction plate and slippers. The retraction plate and slippers follow the angle of swashplate (7). Thus, a change in the angle of swashplate (7) changes the stroke of the pumping pistons.Swashplate (7) does not rotate. Swashplate (7) changes angles by pivoting. The greater the angle of swashplate (7), the longer the stroke of the pumping pistons. The smaller the angle of swashplate (7), the shorter the stroke of the pumping pistons. When swashplate (7) is at the maximum angle position, the stroke of the pumping pistons is maximized. When swashplate (7) is at the minimum angle position of approximately zero degrees, the stroke of the pumping pistons is minimized.Swashplate (7) can change angles very quickly. Swashplate (7) can move from the minimum angle position to the maximum angle position in about 10 milliseconds.The movement of control piston (2) regulates the angle of swashplate (7). The movement of control piston (2) is regulated by pressure compensator valve (1) .Excess hydraulic oil from pump outlet (4) flows into the body of the cushion-hitch piston pump. This excess hydraulic oil lubricates the cushion-hitch piston pump. This excess hydraulic oil also flows through a drain line to the supply line for the implement pump.