PUMP GP-GEAR 2078236 - Caterpillar

Illustration 1 g01489134
Partial schematic of swing circuit (1) Swing motor (2) Motor rotary group of the swing motor (3) Passage (4) Relief valve (5) Check valve (6) Passage (7) Relief valve (8) Check valve (9) Port (10) Makeup port (11) Port (12) Passage (13) Makeup line (14) Oil cooler (15) Hydraulic tank (17) Slow return check valve (18) Return line
Illustration 2 g01489137
Swing motor compartment (1) Swing motor (4) Relief valve (7) Relief valve (13) Makeup lineWhen the rotation of the swing motor is stopped, both the inlet and the outlet ports of the swing control valve are blocked. No pump oil is sent to the swing motor. The mass (weight and size) of the upper structure causes the upper structure to attempt to continue rotation. Part of the oil in the swing motor is lost in the form of internal leakage. The oil loss causes a vacuum condition to occur at port (9). To prevent this vacuum condition, oil from return line (14) goes through makeup line (13), makeup port (10), check valve (5) and passage (3) into the motor rotary group (2).