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| Illustration 1 | g06015917 |
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Hydraulic schematic for travel hydraulic system (1) Case drain (2) Left travel motor (3) Right travel motor (4) Case drain (5) Swivel (6) Main control valve (7) Left travel control valve (8) Right travel control valve (9) Oil that is supplied to the main control valve (10) Oil that is supplied to the main control valve (11) Hydraulic pump (12) HPU changeover valve (13) Hydraulic tank | |
Right travel motor (3) and left travel motor (2) are supplied with oil from hydraulic pump (11). The hydraulic pump supplies the oil through main control valve (6) and swivel (5) to the travel motors.
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| Illustration 2 | g02448377 |
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Right travel motor (3) Right travel motor | |
The travel motors are slow running gerotor type motors. The case drain is internal in the motor.
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| Illustration 3 | g02450236 |
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Right travel drive (3) Right travel motor (14) Sprocket | |
Oil is supplied to right travel motor (3) by the main pump through the swivel. When the main pump supplies hydraulic oil to the right travel motor, the motor rotates and the motor torque is transferred to sprocket (14). Sprocket (14) transfers the torque to the right track.
The travel speed can be controlled through fine movements of the travel levers.
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| Illustration 4 | g02450157 |
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Travel operation (2) Left travel motor (3) Right travel motor (15) Left travel control lever (16) Right travel control lever (17) Idler (18) Forward direction (19) Reverse direction | |
The direction of machine movement is determined by the direction of the lower structure of the machine. For normal operation, the idlers (17) are toward the front of the machine and travel motors (3) and (2) are toward the rear of the machine. When the machine is arranged for normal travel and control levers (15) and (16) are pushed forward, the machine moves forward. The machine travels backward when the control levers are pulled backward. If the upper structure is turned 180 degrees, the operating directions for the travel levers are reversed.
When the machine is in the normal travel position and when one of the travel levers is moved forward, the respective track travels forward. The machine turns because the stationary track acts as the pivot point. This type of turn is called a pivot turn.
The machine will perform a spot turn to change the travel direction within a narrow space. To perform a spot turn, move one travel lever to the rear and move the other travel lever forward at the same time. The machine will spot turn around the center axis of the machine.
Reference: Refer to the Operation and Maintenance Manual, "Travel Control" for more information on the operation of the travel levers.
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| Illustration 5 | g02451216 |
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Right travel motor (travel STOP) (3) Right travel motor (20) Motor rotary group (21) Passage (22) Check valve (23) Brake valve (24) Port (25) Port | |
Each travel motor contains a travel brake valve. The travel brake valve is located within the travel motor. Travel brake valve (23) prevents the occurrence of a shock load during a travel stop, cavitation, and overrun. Travel brake valve (23) also keeps the machine from moving when parked on a slope.
When the travel control levers are returned to the NEUTRAL position during machine movement, the oil delivery from the pumps is blocked from the travel motors. The pressure at port (24) decreases. Spring force moves brake valve (23) to the NEUTRAL position. The mass (weight and size) of the machine causes the travel motor to continue to rotate. A sudden pressure increase occurs in passage (21). Check valve (22) blocks the oil from returning to the hydraulic tank and therefore stops motor rotary group (20) from rotating.