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| Illustration 1 | g00790869 |
Hydraulic Schematic for the Travel Circuit (1) Right travel motor (2) Motor rotary group (3) Swashplate control piston (speed) (4) Line relief valve (forward) (5) Brake valve (6) Check and relief valve (7) Brake pilot valve (8) Left travel motor (9) Brake pilot valve (10) Check and relief valve (11) Brake valve (12) Line relief valve (reverse) (13) Swashplate control piston (speed) (14) Motor rotary group (15) Parking brake (16) Displacement change valve (17) Line relief valve (reverse) (18) Line relief valve (forward) (19) Displacement change valve (20) Parking brake (21) Swivel (22) Pilot resolver shuttle valve (23) Main implement valve (24) Travel control valve (right) (25) Travel control valve (left) (26) Pilot manifold (27) Travel speed solenoid (high speed or low speed) (28) Travel pilot control valve (29) Saw Pump (30) Lower pump (31) Upper pump (32) Oil cooler (33) Hydraulic activation control valve (34) Pilot pump (35) Hydraulic oil tank | |
Travel Control
Introduction
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| Illustration 2 | g00790772 |
Right Travel Motor (1) Motor rotary group. (3) Line relief valve (forward). (5) Brake valve. (6) Check and relief valve. (7) Brake pilot valve. (16) Line relief valve (reverse). | |
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| Illustration 3 | g00790773 |
Right Side Travel Motor (36) Track. (37) Sprocket. (38) Final drive. | |
The output flow from upper pump (31) flows through travel control valve (25) and swivel (21) to left travel motor (8). The output flow from lower pump (30) flows through travel control valve (24) and swivel (21) to right 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 the final drive. Final drive (38) increases the torque and the rotational force drives track (36) via sprocket (37).
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| Illustration 4 | g00617507 |
Operator switches (right console) Travel speed control switch | |
The travel speed can be adjusted by the slight operation of the travel pedals. The travel speed can also be controlled by the travel speed control switch. This changes the travel speed when the travel pedals are moved to the maximum position. The travel speed control switch can be set at the LOW SPEED position (tortoise) or the HIGH SPEED position (rabbit). During travel on a flat surface or during gradual downhill travel, the travel speed is set at the HIGH SPEED position in order to realize increased mobility.
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| Illustration 5 | g00791004 |
Operation of Travel (1) Right travel motor. (8) Left travel motor. (39) Footrest. (40) Left travel pedal. (41) Right travel pedal. (42) Footrest. (43) Front idlers. (44) Forward travel. (45) Cab. (46) Reverse travel. | |
The direction of travel is relative to the position of the lower structure. For normal travel, idlers (43) are positioned in front of cab (45). Travel motors (1) and (8) are positioned to the rear of the cab. With the machine in the normal position of travel, depress the top of the travel pedals (40) and (41). The machine will travel in forward direction (44). When the bottom of the travel pedals (40) and (41) are depressed the machine travels in reverse direction (46) .
When cab (45) is rotated by 180 degrees, travel motors (1) and (8) are positioned in front of the cab. The direction of travel and the operation of the travel pedals (40) and (41) are reversed from the normal travel direction.
When the machine is in the normal position of travel and when one of the travel pedals (40) or (41) 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.
Forward Travel
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| Illustration 6 | g00791033 |
Main Implement Valve (24) Travel control valve (right). (25) Travel control valve (left). | |
Move the hydraulic activation control lever to the UNLOCKED position. This allows the pilot system oil to flow to travel pilot control valve (28) .
When both of the travel pedals are operated, pilot system oil pressure flows from travel pilot control valve (28) through pilot lines to right travel control valve (24) and left travel control valve (25). The pilot system oil pressure also flows from travel pilot control valve (28) to pilot resolver shuttle valve (22).
The pilot system oil pressure shifts the spools in both of the travel control valves downward. The travel control valves allow the pump oil from upper pump (31) and lower pump (30) to flow to swivel (21). The swivel transfers the pump oil from the rotating upper structure to the lines in the lower structure. The pump oil flows to right travel motor (1) and left 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 pedal is moved to the FORWARD TRAVEL position, pilot system oil pressure from travel pilot control valve (28) flows through the pilot line to left travel control valve (25). The spool in left travel control valve (25) shifts downward. The pump oil from upper pump (31) flows through the center passage of left travel control valve (25). The pump oil flows out of left travel control valve (25) through a supply line to swivel (21). The pump oil flows from swivel (21) through a supply line to left travel motor (8) .
The pump oil from upper pump (31) enters left travel motor (8) and flows through brake valve (11) and through an internal passage to motor rotary group (14). At the same time, a portion of the pump oil from upper pump (31) flows through a passage to the shuttle valve. The oil flows through the shuttle valve through an internal passage to brake pilot valve (9). Brake pilot valve (9) sends oil to parking brake (20). The parking brake inside the final drive is released and the pump oil from upper pump (31) causes left travel motor (8) to rotate in the forward direction.
Low Speed
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| Illustration 7 | g00794893 |
Travel Speed Solenoid Valve The travel speed solenoid valve is located on the pilot manifold. | |
When the travel speed control switch is set at the LOW SPEED position, the travel speed solenoid is energized. The pilot oil is blocked. The spool in the displacement change valve shifts. A portion of the oil flows from upper pump (31) through internal passages and displacement change valve (19) to swashplate control piston (13). As a result, swashplate control piston (13) moves the swashplate of the motor to the maximum displacement position. At the same time, the oil that acts on swashplate control piston (13) flows into the case drain of the travel motor. One rotation of motor rotary group (14) displaces a larger amount of oil flow. The rotational speed of left travel motor (8) decreases. The left track moves at a slower speed. The left track moves slowly and better traction is achieved.
The return oil from motor rotary group (14) flows through an internal passage, brake valve (11), check and relief valve (10), an external line and swivel (21). The return oil then flows to left travel control valve (25). The return oil flows from left travel control valve (25) to a return line. The return oil passes through oil cooler (32) to hydraulic tank (35) .
Right travel motor (1) receives the oil delivery from lower pump (30). The right travel motor functions in the same manner as the left travel motor, when the travel control switch is in the LOW SPEED position.
High Speed
When the travel speed control switch is set at the HIGH SPEED position, the travel speed solenoid is de-energized. Pilot system oil flows through travel speed solenoid valve (27). Pilot system oil pressure flows through an external line to displacement change valve (19). The spool in displacement change valve (19) shifts. A portion of the oil from upper pump (31) flows through displacement change valve (19) to swashplate control piston (13). Swashplate control piston (13) moves the swashplate of the motor to the minimum displacement position. At the same time, the oil that acts on swashplate control piston (13) flows into the case drain of the travel motor. One rotation of motor rotary group (14) displaces a smaller amount of oil flow. The rotational speed of left travel motor (8) increases.
The return oil from motor rotary group (14) flows through an internal passage, brake valve (11), check and relief valve (10), an external line and swivel (21). The return oil then flows to left travel control valve (25). The return oil flows from left travel control valve (25) to a return line. The return oil passes through oil cooler (32) to hydraulic tank (35) .
Right travel motor (1) receives the oil from lower pump (30). The right travel motor functions in the same manner as the left travel motor, when the travel control switch is in the HIGH SPEED position.