Introduction
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| Illustration 1 | g00948841 |
Travel Motor (1) Left travel motor (2) Travel brake valve | |
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| Illustration 2 | g00584146 |
Travel Drive (3) Track (4) Sprocket (5) Final drive | |
The left travel motor and the right travel motor are supplied with oil through a swivel or from control valves. The travel motors transfer torque to the final drives. The final drives reduce the speed of the travel motors and the final drives increase the torque of the travel motors. The increased torque from the travel drive turns the track through the sprocket.
The travel motors are capable of two travel speeds, high or low. When the machine is travelling on a flat surface or on a moderate downward slope, select the high position for increased mobility.
The direction of travel (forward or reverse) is relative to the position of the lower structure. For normal travel, the idler is positioned in front of the machine and the travel motors are positioned to the rear of the machine.
A pivot turn is made when the travel direction of the machine is changed. When only one of the travel levers or one of the travel pedals is moved forward, the respective track travels forward. Since the opposite track is stationary, the machine turns with the stationary track as the pivot point. This is called a pivot turn.
A spot turn operation is made when the travel direction of the machine is changed in tight quarters. To complete a spot turn operation, move one travel lever or one travel pedal to the rear and move the other travel lever or the other travel pedal forward at the same time. The tracks will travel in opposite directions. The machine makes a spot turn operation with a minimum radius and the center of the machine is the pivot point.
Forward Travel Operation
When the travel control lever and/or pedals are operated for forward travel, pump oil is supplied through the swivel. Pump oil enters each counterbalance valve to the brake pilot valve and the parking brake. The parking brake releases causing each of the travel motors to rotate in the forward direction.
Low Speed Travel
When the travel motor is in the LOW SPEED MODE position, part of the pilot oil enters the displacement change valve to the swashplate piston. The swashplate is turned in the direction of an increased angle and the swashplate remains in the maximum angle position. More oil is now required to turn the travel motors, and the travel motors will rotate at a lower speed. The tracks will travel at a lower speed and the drawbar pull of the tracks will be increased.
High Speed Travel
When the travel motor is in the HIGH SPEED MODE position, the travel speed increases. Oil from the pilot pump flows to the displacement change valve. The spool in the displacement change valve will shift. As the spool shifts, oil from the pump flows through the displacement change valve to the piston. The oil that is pushed by the piston goes through the displacement change valve to the motor case drain.
The pressure oil pushes the piston, which decreases the angle of the swashplate, and the swashplate is held in the minimum angle position. Less oil is now required to turn the travel motors. The motor turns at a higher speed.