Type "A" Oil Makeup Operation
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| Illustration 1 | g00862220 |
Oil Makeup Circuit (1) Motor rotary group (2) Left travel motor (3) Passage (4) Check valve (5) Line (6) Swivel (7) Line (8) Passage (9) Left travel control valve (10) Passage (11) Return passage | |
Return oil from the travel control valve is used as makeup oil to prevent a vacuum condition in the travel motor when operation is stopped.
The oil makeup operation is given with respect to left travel. For right travel, the oil makeup operation is identical.
If the left travel control lever is returned to the NEUTRAL position in order to stop left travel, supply of pump oil to left travel motor (2) is blocked at passage (10). The left travel motor continues to rotate because the machine is still in motion. A negative oil pressure at passage (3) of motor rotary group (1) opens check valve (4) .
With left travel control valve (9) in the NEUTRAL position, return oil from passage (11) flows to passage (8). The return oil then goes through line (7), swivel (6), and line (5) into left travel motor (2). The oil passes through opened check valve (4) and passage (3) into motor rotary group (1). This makeup oil eliminates the possibility of cavitation in the travel motor.
Type "B" Oil Makeup Operation
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| Illustration 2 | g00470336 |
Oil Makeup Circuit (21) Left travel motor (22) Motor rotary group (23) Passage (24) Check valve (25) Line (26) Swivel (27) Line (28) Passage (29) Return passage (30) Passage (31) Left travel control valve | |
Return oil from the travel control valve is used as makeup oil to prevent a vacuum condition in the travel motor when operation is stopped.
The oil makeup operation is given with respect to left travel. For right travel, the oil makeup operation is identical.
If the left travel control lever is returned to the NEUTRAL position in order to stop left travel, supply of pump oil to left travel motor (21) is blocked at passage (30). The left travel motor continues to rotate because the machine is still in motion. A negative oil pressure at passage (23) of motor rotary group (22) opens check valve (24) .
With left travel control valve (31) in the NEUTRAL position, passage (29) is connected to line (27) by passage (28). Oil from the hydraulic tank flows through passage (29), passage (28) and line (27) into swivel (26). The oil then flows through line (25), check valve (24) and passage (23) into motor rotary group (22). This makeup oil eliminates the possibility of cavitation in the travel motor.