O-RING 0993342 - Caterpillar

When the swing control lever is in the NEUTRAL position, no input signal is sent to the machine electronic control module from the swing control lever. The machine electronic control module sends a low current signal to the proportional solenoid at the swing pump regulator. The swing pump regulator is now in the STANDBY position.The pump servo pistons are connected to the swing pump swashplate (1). Full pilot system pressure flows through shuttle valve (3) to maximum angle servo piston (4). The low electrical current that is sent to proportional solenoid (9) produces a low force (FS). Spool (13) is positioned to the left against force (FS) by the force of spring (15), guide (14) and spring (10). Pilot oil pressure in passage (6) is metered past the lands of spool (13). Pilot oil is also metered through orifice (11) into center passage (12) of spool (13) and flows to the case drain. The pilot oil pressure is reduced. This reduced pilot oil pressure also flows through passage (8) to minimum angle servo piston (7). The larger minimum angle servo piston also has a spring in order to assist in moving the servo. The combination of spring force and reduced pilot system pressure at the minimum angle servo piston positions the swing pump swashplate for minimum pump flow.UPSTROKE Position
Illustration 2 g01019320
Swing pump regulator at the start of the UPSTROKE position (1) Swashplate (2)