PUMP GP-MAIN HYDRAULIC 2667944 - Caterpillar

Illustration 1 g03238836
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 (16) Slow return check valve (17) Return line
Illustration 2 g03237519
Swing motor compartment (1) Swing motor (4) Relief valve (7) Relief valve (13) Makeup lineWhen the rotation of swing motor (1) is stopped, both the inlet and the outlet ports are blocked. No pump oil is sent to swing motor (1). The mass (weight and size) of the upper structure causes the upper structure to attempt to continue rotation. Part of the oil in swing motor (1) 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 (17) goes through makeup line (13). The makeup oil then flows through makeup port (10), check valve (5), and passage (3) into the motor rotary group (2).