TRUNNION AS 1U1273 - Caterpillar

Illustration 1 g02788320
Swing Pump Group
(1) Line from joystick
(2) Swing system proportional pilot limiting solenoid valve
(3) Line from joystick
(4) Orifice check valve
(5) Resolver
(6) Orifice check valve
(7) Charge filter
(8) Throttle spool piston
(9) Throttle spool piston
(10) Swing pump
(11) Actuator piston
(12) Swing charge pump
(13) Line from swing motor
(14) Crossover relief valve
(15) Charge relief valve
(16) Pressure cutoff valve
(17) Shuttle valve
(18) Line to swing motor
(19) Makeup valve
(20) Fan drive pump Charge pump (12) is used to keep the closed loop swing system charged with oil and charge pump (12) provides cooling and lubrication.During the swing operation, swing pump (10) is upstroked to direct flow to the swing motor.During a swing to the right, pilot pressure from the swing pilot control enters the pump control at port (1). The pilot pressure goes through orifice check valve (4) to the left end of throttle spool piston (8). The throttle slots in the end of spool (8) direct pilot pressure to the left side of actuator piston (11). This action will start upstroking swing pump (10).Pilot oil from orifice check valve (8) also flows to the left side of resolver valve (5). Resolver (5) moves to the right and pilot oil is directed to the large shoulder area of both throttle spool pistons. Pilot oil also goes through