WIRE A-SPARK 7W8665 - Caterpillar

Slow return check valve (18) is located downstream of return line (16). Slow return check valve (18) replenishes the lost oil.When all of main control valves (17) are in the NEUTRAL position, the oil from the upper pump and the lower pump flows through return line (16) to the tank. Check valve (18) causes a resistance to the oil flow in return line (16). This maintains the oil pressure at 290 kPa (42 psi).The return line provides oil to the swing motor in order to replenish oil. The oil flows through port (2) and passage (9) .When the swing speed is decreased by the operator, oil pressure at port (12) decreases. The swing control valve is partially open. The oil continues to flow through port (13) to return line (16). The oil pressure at port (13) is lower than the pressure setting of relief valve (7). This causes the valve to remain blocked. Makeup oil flow is blocked from check valve (11) to passage (1). A vacuum condition occurs at port (12). This causes check valve (11) to supply makeup oil from makeup line (10) to motor rotary group (4). This eliminates the vacuum condition.When the swing motor is stopped or decelerated during a swing operation in the opposite direction, oil is supplied through port (13) and check valve (14). Check valve (14) operates in the same manner as check valve (11). Check valve (14) prevents a vacuum condition in the swing motor.Anti-Reaction Valve
Illustration 6 g00705356
Side of swing motor (1) Block (2) Swing motor (3) Anti-reaction valve (4) Anti-reaction valveStopping the upper structure is difficult due to the motion of the upper structure. The blocked oil in the outlet of the swing motor flows to the motor rotary group. This causes the upper structure to try to swing in the reverse direction. Anti-reaction valves (3) and (4) ensure an exact swing movement with a minimal shock load at stop. Anti-reaction valves (3) and (4) are located in block (1) which is attached to swing motor (2).
Illustration 7 g00705367
Anti-reaction valve (neutral position) (1) Block (3) Anti-reaction valve (4) Anti-reaction valve (5) Motor rotary group (6) Passage (7) Port (8) Passage (9) Passage (10) Passage (11) Port (12) Passage (13) Spring (14) Valve seat (15) Passage (16) Plunger (17) Passage (18) Spring (19) Piston chamber (20) Passage (21) Spring chamber (22) Spring (23) Valve seat (24) Plunger (25) Spring (26) PistonWhen the swing control is in the NEUTRAL position, pump oil is not supplied to motor rotary group (5). Plunger (24) is located in anti-reaction valve (3). Plunger (24) shifts downward because of the force of spring (25). Plunger (24) is stopped by piston (26). Valve seat (23) shifts downward by the force of spring (22). Valve seat (23) comes in contact with plunger (24). Plunger (16) and valve seat (14) in anti-reaction valve (4) are shifted downward by the force of spring (13) until contact is made with piston (34). Valve seat (14) moves downward by the force of spring (13)