Forward Travel
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| Illustration 1 | g01623425 |
325 Variable gauge undercarriage (forward travel) (1) Left travel motor (2) Left parking brake (3) Relief valve (4) Relief valve (5) Reducing valve (6) Relief valve (7) Right parking brake (8) Right travel motor (9) Relief valve (10) Reducing valve (11) Swivel (12) Right travel control valve (13) Left travel control valve (14) Hydraulic tank (15) Idler pump (16) Drive pump (17) Pilot pump | |
When both of the travel levers/pedals are operated, pilot system oil pressure flows from the travel pilot control valve, in the upper structure, through pilot lines and to right travel control valve (12) and left travel control valve (13). The pilot system oil pressure shifts the spools in both of the travel control valves in an upward direction. The travel control valves allow the oil delivery from drive pump (16) and idler pump (15) to flow to swivel (11). The swivel transfers the oil delivery from the rotating upper structure to the lines in the lower structure. The oil delivery flows to left travel motor (1) and right travel motor (8) .
Note: The right and left travel controls function in the same manner. The explanation for the left travel control will be used to explain both the right and left travel controls.
When the left travel lever/pedal is moved to the FORWARD TRAVEL position, pilot system oil pressure from the travel pilot control valve flows to left travel control valve (13). The spool in the left travel control valve shifts in an upward direction. The oil delivery from idler pump (15) flows to left travel control valve (13), and swivel (11) to left travel motor (1) .
The oil delivery from idler pump (15) enters left travel motor (1) and flows to the motor rotary group. At the same time, a portion of the oil delivery from idler pump (15) flows to parking brake (2). The parking brake is released and the oil delivery from idler pump (15) causes the motor to rotate.
Travel Control
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| Illustration 2 | g01623457 |
(7) Right parking brake (8) Right travel motor | |
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| Illustration 3 | g01623468 |
Typical final drive (18) Left final drive (19) Left track (20) Sprocket | |
The output flow from the drive pump flows through swivel (11) to right travel motor (8). The output flow from idler pump (15) flows through swivel (11) to left travel motor (1). The pump delivery flow causes rotation of the travel motors. The torque of the travel motors is transmitted to the final drives. The rotational speed of the travel motors is reduced by gear reduction in final drive (18). Final drive (18) increases the torque and the rotational force drives track (19) via sprocket (20).
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| Illustration 4 | g01623477 |
Operation of travel (21) Left travel lever/pedal (22) Right travel lever/pedal (23) Idlers (24) Forward travel (25) Cab (1) Left travel motor (8) Right travel motor (26) Reverse travel | |
The direction of travel is relative to the position of the lower structure. For normal travel, idlers (23) are positioned in front of cab (25) and travel motors (8) and (1) to the rear of the cab. With the machine in the normal position of travel, move the travel levers/pedals (21) and (22) forward. The machine will travel in forward direction (24). This movement is called forward travel. When the travel levers/pedals (21) and (22) are moved toward the operator, the machine travels in reverse direction (26). This direction is called reverse travel.
When cab (25) is rotated 180 degrees, travel motors (8) and (1) are positioned in front of the cab. The direction of travel and the operation of the travel levers/pedals (21) and (22) are reversed from the normal travel direction.
When the machine is in the normal position of travel and when one of the travel levers/pedals (21) or (22) is moved forward, the respective track travels forward. The machine turns because the stationary track acts as the pivot point. This is called a pivot turn.
This machine will spot turn in order to change the travel direction of the machine in a narrow space. To complete a spot turn operation, move one travel lever/pedal to the rear and move the other travel lever/pedal forward at the same time. One track will travel to the rear and the other track will travel forward. The machine will spot turn around the center axis of the machine.