The Oil Makeup Circuit On CIPI Undercarriage Arrangements Which Are Based On 325 Track Type Excavators
 | |
| Illustration 1 | g00936644 |
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.
Oil makeup operation is given with respect to left travel. Oil makeup operation for right travel operates in the same manner.
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 of the mass of the machine. A negative pressure at passage (3) of motor rotary group (1) opens check valve (4) .
With left travel control valve (9) in NEUTRAL position, return oil from passage (11) flows to passage (8). The return oil goes through line (7), through swivel (6), through line (5), and into left travel motor (2). The oil passes through opened check valve (4), through passage (3), and into motor rotary group (1) as makeup oil. The makeup oil circuit eliminates the possible occurrence of cavitation in the travel motor.
The Oil Makeup Circuit On CIPI Undercarriage Arrangements Which Are Based On 325B Track Type Excavators
 | |
| Illustration 2 | g00586686 |
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.
Oil makeup operation is given with respect to left travel. Oil makeup operation for right travel operates in the same manner.
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 of the mass of the machine. A negative pressure at passage (3) of motor rotary group (1) opens check valve (4) .
With left travel control valve (9) in NEUTRAL position, return oil from passage (11) flows to passage (8). The return oil goes through line (7), through swivel (6), through line (5), and into left travel motor (2). The oil passes through opened check valve (4), through passage (3), and into motor rotary group (1) as makeup oil. The makeup oil circuit eliminates the possible occurrence of cavitation in the travel motor.
The Oil Makeup Circuit On CIPI Undercarriage Arrangements Which Are Based On 325C Track Type Excavators
 | |
| Illustration 3 | g00821082 |
Oil makeup operation (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 | |
In order to prevent cavitation in the travel motor during travel stop, makeup oil is supplied to the travel motor.
The following description is given for travel stop of the left travel motor. The right travel motor functions in the same manner as the left travel motor.
During travel stop, the travel levers/pedals are moved to the NEUTRAL position. The oil delivery from the left pump through passage (8) is blocked at travel control valve (9). The oil delivery from the left pump is not supplied to the left travel motor.
Since no oil delivery is supplied to left travel motor (2), the travel motor will attempt to stop. However, the travel motor will continue to rotate because of the inertia (weight and size) of the machine. This causes a vacuum condition in passage (3) of the travel motor.
When travel control valve (9) is in the NEUTRAL position, return oil flows from return passage (11) through passage (8). The return oil then flows through line (7), swivel (6), line (5), check valve (4) and passage (3) to motor rotary group (1) as makeup oil. This makeup oil prevents cavitation in the travel motor during travel stop.
Makeup oil is supplied for forward travel in the same manner as reverse travel.