TM 5-2410-240-23-1
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ELECTRO-HYDRAULIC CONTROLS CONTINUED
5. Forward Travel
The machine ECM (Figure 9, Item 2) interprets two signals and determines that the joystick (Figure 9, Item 1) is in
the FORWARD position. The machine ECM sets the duty cycle for the motor displacement control solenoids
(Figure 9, Items 7 and 8) between 33% and 70%. These solenoids are located in the left and right hydrostatic drive
motors, respectively.
The machine ECM (Figure 9, Item 2) also sets the duty cycle for the reverse solenoids (Figure 9, Items 5 and 6) at
less than 23.5% and the duty cycle for the forward solenoids (Figure 9, Items 3 and 4) between 26% and 88.5%.
These solenoids adjust the proportional solenoid valves in the left and right side hydrostatic pumps, respectively.
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The duty cycles determine the angle of the pump and motor swashplates. The machine
ECM (Figure 9, Item 2) varies duty cycles based on signals received from the travel speed
switch in the joystick (Figure 9, Item 1). The machine ECM also adjusts duty cycles based
on signals received from the engine speed sensor (Figure 9, Item 11) and the motor speed
sensors (Figure 9, Items 9 and 10) in order to prevent an overspeed, underspeed, or stall
condition, and to ensure the machine is tracking in a straight line.
Figure 9. Machine ECM Inputs and Outputs for Forward Travel.
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