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| Illustration 1 | g06315061 |
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Hydraulic schematic for FORWARD TRAVEL (1) Left travel motor (2) Swashplate (3) Motor rotary group (4) Swashplate control piston (5) Parking brake (6) Passage (7) Displacement change valve (8) Passage (9) Counterbalance valve (10) Passage (12) Passage (14) Line (pilot system oil pressure) (15) Right travel motor (17) Swashplate (18) Passage (19) Swashplate control piston (20) Passage (21) Passage (22) Passage (23) Passage (24) Displacement change valve (25) Passage (27) Line (28) Line (29) Swivel (30) Line (31) Line (32) Line (pilot system oil pressure) (33) Travel pilot control valve (34) Pilot line (forward right travel) (35) Pilot line (forward left travel) (36) Line (37) Line (38) Travel pressure switch (39) Passage (40) Passage (41) Passage (42) Right travel control valve (43) Passage (44) Return passage (45) Left travel control valve (46) Pressure sensor (main pump) (48) Travel speed solenoid valve (49) Return line (50) Main pump (64) Travel pilot limit PRV | |
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| Illustration 2 | g03697483 |
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Main control valve (42) Right travel control valve (45) Left travel control valve | |
When both travel levers/pedals are operated, pilot system oil pressure flows from travel pilot control valve (33) through pilot line (35) to left travel control valve (45) and through pilot line (34) to right travel control valve (42). The pilot system oil pressure shifts both travel control valves (42) and (45) in a downward direction. Travel control valves (42) and (45) allow the oil delivery from main pump (50) to flow to swivel (29). Swivel (29) 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 (15).
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 travel pilot control valve (33) flows through pilot line (35) to left travel control valve (45). Left travel control valve (45) shifts in a downward direction. The oil delivery from main pump (50) flows through passage (43) and passage (40). The oil then flows through left travel control valve (45), passage (39), line (36), and to swivel (29). Oil then flows through line (28) and into left travel motor (1).
The oil delivery from main pump (50) enters left travel motor (1) and flows to counterbalance valve (9). The oil flow then divides into two paths. In one path , the oil flows through passage (6) to motor rotary group (3). In the other path, the oil flow through passage (10) to parking brake (5). Parking brake (5) is released and the oil delivery from main pump (50) causes the motor to rotate.
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| Illustration 3 | g06315071 |
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(1) Left travel motor
(53) Travel brake valve | |
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| Illustration 4 | g03697988 |
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Final drive (54) Track (55) Sprocket (56) Final drive | |
The output flow from main pump (50) flows through swivel (29) to right travel motor (15) and left travel motor (1). The pump delivery flow causes rotation of travel motors (1) and (15). The torque of travel motors (1) and (15) is transmitted to the final drives. The rotational speed of travel motors (1) and (15) is reduced by gear reduction in final drive (56). Final drive (56) increases the torque and the rotational force drives track (54) via sprocket (55).
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| Illustration 5 | g03697986 |
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Keypad (right console) (57) Travel speed control switch | |
The travel speed can be adjusted by the slight operation of the travel levers/pedals (58) and (59). The travel speed can also be controlled by travel speed control switch (57). This changes the travel speed when travel levers/pedals (58) and (59) are moved to the maximum position. Travel speed control switch (57) can be set at the LOW SPEED position or the HIGH SPEED position. When travel speed control switch (57) is set at the LOW SPEED position, the tortoise appears on the default message display of the monitor. When travel speed control switch (57) is set at the HIGH SPEED position, the rabbit appears on the default message display of the monitor. 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.
When travel speed control switch (57) is set at the HIGH SPEED position, the pressure sensors for pump delivery pressure detect the change in pump load. If the pressure sensors detect a high load, the travel speed is automatically adjusted to LOW SPEED. If the pressure sensors detect a small load, the travel speed is automatically adjusted to HIGH SPEED.
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| Illustration 6 | g03697984 |
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Operation of travel (1) Left travel motor (15) Right travel motor (58) Left travel lever/pedal (59) Right travel lever/pedal (60) Reverse travel (61) Cab (62) Idler (63) Forward travel | |
The direction of travel is relative to the position of the lower structure. For normal travel, idler (62) is positioned in front of cab (61) and travel motors (1) and (15) to the rear of the cab. With the machine in the normal position of travel, move the travel levers/pedals (58) and (59) forward. The machine will travel in forward direction (63). This movement is called forward travel. When the travel levers/pedals (58) and (59) are moved toward the operator, the machine travels in reverse direction (60). This direction is called reverse travel.
When cab (61) is rotated by 180 degrees, travel motors (1) and (15) are positioned in front of the cab. The direction of travel and the operation of the travel levers/pedals (58) and (59) 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 (58) or (59) is moved forward, the respective track travels forward. The machine turns because the stationary track acts as the pivot point. This action 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.
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| Illustration 7 | g03697483 |
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Main control valve (42) Right travel control valve (45) Left travel control valve | |
When both of the travel levers/pedals (58) and (59) are operated, pilot system oil pressure flows from travel pilot control valve (33) through pilot line (34) to left travel control valve (45) and pilot line (35) to right travel control valve (42). The pilot system oil pressure shifts the spools in both of the travel control valves (42) and (45) for FORWARD TRAVEL operation. Travel control valves (42) and (45) allow the oil delivery from main pump (50) to flow through the travel supply lines to swivel (29). Swivel (29) 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 (15).
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 left travel lever/pedal (58) is moved to the FORWARD TRAVEL position, pilot system oil pressure from travel pilot control valve (33) flows through pilot line (35) to left travel control valve (45). The spool in left travel control valve (45) shifts for FORWARD TRAVEL operation. The oil delivery from main pump (50) in passage (40) flows through left travel control valve (45), passage (39), line (36), and swivel (29) to left travel motor (1).
The oil delivery from main pump (50) enters left travel motor (1) and flows through counterbalance valve (9) to motor rotary group (3). At the same time, a portion of the oil delivery from the main pump flows through passage (10) to parking brake (5). Parking brake (5) is released and the oil delivery from main pump (50) causes the motor to rotate.
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| Illustration 8 | g06315078 |
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Left travel motor (LOW SPEED) (1) Left travel motor (2) Swashplate (3) Motor rotary group (4) Swashplate control piston (6) Passage (7) Displacement change valve (8) Passage (9) Counterbalance valve (12) Passage (32) Pilot line (46) Pressure sensor (main pump) (48) Travel speed solenoid valve (50) Main pump (57) Travel speed control switch (58) Left travel lever/pedal (B) Indicator for HIGH SPEED (C) Indicator for LOW SPEED (D) Machine ECM (E) Main control valve | |
When travel speed control switch (57) is set at the LOW SPEED position (C), an electrical signal is sent to machine ECM (D). Machine ECM (D) does not energize travel speed solenoid valve (48) and pilot system oil pressure does not flow through pilot line (32) to displacement change valve (7). The spool in displacement change valve (7) does not shift. A portion of the oil flow from pump (50) in passage (6) flows through passage (8) and displacement change valve (7) to swashplate control piston (4). As a result, swashplate control piston (4) moves swashplate (2) to the maximum displacement position. At the same time, the oil that acts on swashplate control piston (4) flows into the case drain of travel motor (1). One rotation of motor rotary group (3) displaces a larger amount of oil flow. The rotational speed of left travel motor (1) decreases. The left track moves slowly and better traction is achieved.
The return oil from motor rotary group (3) flows through passage (12), counterbalance valve (9), line (27), and swivel (29). The return oil then flows through line (37), left travel control valve (45), return passage (44), and return line (49) to the hydraulic tank.
Right travel motor (15) receives the oil delivery from pump (50). Right travel motor (15) functions in the same manner as left travel motor (1) in the LOW SPEED position.
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| Illustration 9 | g03697968 |
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Travel speed solenoid location (48) Travel speed solenoid valve | |
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| Illustration 10 | g06315080 |
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Left travel motor (HIGH SPEED) (1) Left travel motor (2) Swashplate (3) Motor rotary group (4) Swashplate control piston (6) Passage (7) Displacement change valve (8) Passage (9) Counterbalance valve (12) Passage (32) Pilot line (46) Pressure sensor (main pump) (48) Travel speed solenoid valve (50) Main pump (57) Travel speed control switch (58) Left travel lever/pedal (B) Indicator for HIGH SPEED (C) Indicator for LOW SPEED (D) Machine ECM (E) Main control valve | |
When travel speed control switch (57) is set at the HIGH SPEED position, an electrical signal is sent to machine ECM (D). Pressure sensor (46) also send an electrical signal to machine ECM (D). If the travel load is light and when the pump delivery pressure is below a certain pressure, machine ECM (D) energizes travel speed solenoid valve (48). Pilot system oil pressure flows through travel speed solenoid valve (48) and line (32) to displacement change valve (7). The spool in displacement change valve (7) shifts. A portion of the oil delivery from main pump (50) flows through displacement change valve (7) to swashplate control piston (4). Swashplate control piston (4) moves swashplate (2) to the minimum displacement position. At the same time, the oil that acts on swashplate control piston (4) flows into the case drain of travel motor (1). One rotation of motor rotary group (3) displaces a smaller amount of oil flow. The rotational speed of left travel motor (1) increases. The left track moves at a faster speed.
The return oil from motor rotary group (3) flows through passage (12), counterbalance valve (9), line (27), and swivel (29). The return oil then flows through line (37), left travel control valve (45), return passage (44), and return line (49) to the hydraulic tank.
Right travel motor (15) receives the oil delivery from main pump (50). Right travel motor (15) functions in the same manner as left travel motor (1) in HIGH SPEED position.
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| Illustration 11 | g03787312 |
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travel (33) Travel pilot control valves (50) Main pump (64) Travel pilot limit PRV (65) Implement pilot limit PRV (66) Left forward pressure switch (67) Left travel pressure sensor (68) Left reverse travel pressure switch (69) Right forward travel pressure switch (70) Right travel pressure sensor (71) Right reverse travel pressure switch (72) Distribution manifold (73) Pilot control valve (stick and swing) (74) Pilot control valve (bucket and boom) (E) Main control valve (F) Pilot manifold | |
The travel pilot control valve is controlled with the following switches, sensors, and pressure reducing valves:
- Left forward travel pressure switch (66)
- Left reverse travel pressure switch (68)
- Right forward travel pressure switch (69)
- Right reverse travel pressure switch (71)
- left travel pressure sensor (67)
- Right travel pressure sensor (70)
- Travel pilot limit PRV (64)
- Implement pilot limit PRV (65) (if equipped)
When the hydraulic lockout solenoid is energized, pilot oil flows through pilot manifold (F), distribution manifold (72), and to travel pilot limit PRV (64). The travel pilot limit PRV (64) controls the oil flow to travel pilot control valves (33) based on the current signal from the Machine ECM. Travel pilot control valves (33) direct oil to the travel control valves. Travel control valve movement is based on the amount of oil flow from travel pilot control valve (33).
Travel pressure switches (66), (68), (69), and (71) inform the Switch Panel ECM of the machine travel direction based on the pilot pressure. Travel pressure sensors (67) and (70) send a signal to the Machine ECM indicating the pilot oil pressure present at the ends of travel pilot control valves (33). The Machine ECM will process the switch status and sensor signals and sends a corresponding signal to travel pilot limit PRV (64). Travel pilot limit PRV (64) will decrease oil flow to the travel control valves during a counter-rotate operation to ensure the final drives rotate at the same speed in both directions.
If implement pilot limit PRV (65) is equipped, the Machine ECM will also process the switch status and sensor signals and sends a corresponding signal to implement pilot limit PRV (65). Implement pilot limit PRV (65) will decrease oil flow to pilot control valves (73) and (74) during a travel operation to ensure the final drives rotate in the same speed in both directions.