UPPER ROLLER 0932946 - Caterpillar

Illustration 1 g03726371
Pressure circuit for SWING RIGHT operation (partial schematic) (1) Swing motor (2) Passage (supply oil) (3) Check valve (4) Makeup port (5) Relief valve (6) Makeup line (7) Return line (8) Port (supply oil) (9) Motor rotary group (10) Passage (return oil) (11) Check valve (12) Relief valve (13) Passage (14) Port (return oil) (15) Swing control valve (16) Slow return check valve (17) Return line
Illustration 2 g03726373
Swing motor (1) Swing motor (4) Makeup port (5) Relief valve (6) Makeup line (12) Relief valve
Illustration 3 g03726385
Swing relief valve (10) Passage (13) Return passage (18) Orifice (19) Spring (20) Stem (21) Piston chamber (22) Piston (23) Passage (24) Passage (25) Piston chamber (26) Orifice (27) Passage (28) Adjustment plugRelief valves (5) and (12) are located in the head of swing motor (1). Relief valves (5) and (12) limit the pressure in the left and right swing circuits to the swing relief valve setting. This provides a cushion effect at a start or stop of the swing operation.When the swing joystick is returned to the NEUTRAL position during the swing right operation, swing control valve (15) shifts to the NEUTRAL position. Since swing control valve (15) is in the NEUTRAL position, the oil delivery through port (8) to the motor rotary group (9) is now blocked at swing control valve (15). The return oil from motor rotary group (9) through port (14) is also blocked at swing control valve (15) .The mass (weight and size) of the upper structure causes the upper structure to attempt to continue to rotate after the swing joystick is returned to the NEUTRAL position. Motor rotary group (9) is also attempting to continue to rotate. Motor rotary group (9) attempts to draw oil through port (8) and attempts to displace the oil through port (14) .The oil supply to motor rotary group (9) is insufficient. A vacuum condition occurs in passage (2). Return oil is supplied to motor rotary group (9) as makeup oil in order to prevent the vacuum condition. For more information concerning the makeup operation, refer to Systems Operation, "Oil Makeup (Swing System)".Since the flow of return oil from motor rotary group (9) through port (14) is blocked at swing control valve (15), the pressure of the blocked oil