Group 19, Motor Controls
SM 765, Sep ’06 Description • 19-1-1
Traction Control and Motors
The dual AC traction control consists of two motor con-
trols mounted to a single heat-sink plate and enclosed by a
single cover. The right portion of the control is reference
to as the "slave" control and operates the left drive motor.
The left portion of the control is referred to as the "mas-
ter" control and operates the right drive motor. The con-
trol receives inputs from the speed control (accelerator)
pedal, steer tire position sensor (steer pot), direction
switches, foot brake switch, motor encoders, motor ther-
mistors and other miscellaneous switches. The control is
able to proportional reduce the speed of the inside tire
when the truck is in a turn, based on the steer angle input
from the steer sensor. Once the steer angle exceeds a cer-
tain value, the inside wheel will start to reverse. The
speed of the vehicle is controlled by the accelerator con-
trol pedal. For a given pedal position the control will
maintain a set speed, as determined by control parameter
settings. These settings are adjustable to meet your cus-
tomer's needs. One feature that is new to the GEX is
"release braking". This feature will apply a regenerative
braking force every time the driver lifts up off the acceler-
ator pedal. The final travel speed will be determined by
the new pedal position. The control receives motor speed
feedback from the motor encoders which allow for precise
speed regulation. Every motor also has a built-in ther-
mistor which constantly monitors the winding tempera-
ture and reports this information to the control. Should it
sense that the motor is approaching the temperature limit,
the control will cutback motor current until the tempera-
ture decreases. Since it is cutting back current and not
voltage, the top end speed will not be effected, unless on a
grade. Each control also has built-in thermal protection
that will reduce output current should the control
approach the thermal limit.
Lift/Steer Control and Motor
A single motor/pump combination is used for both
hydraulic functions and steering. The motor is controlled
by a dedicated controller. The lift lever is equipped with a
linear potentiometer that measures the distance the lever is
stroked and provides this input to the control. The control
uses this information to increase motor speed in propor-
tion to the distance stroked, providing only the desired
flow rate. Tilt and aux switches mounted on the hydraulic
valve provide unique inputs to the control. The speed of
each function can be programmed independently so that
only the required flow rate is produced, minimizing power
losses. When the key is in the "ON" position and a direc-
tion is selected, the control will operate the motor at a
fixed rpm (roughly 500~600 rpm). This provides adequate
flow for the steering function. If the control receives an
input from the lift potentiometer, tilt or aux switches, then
it will ramp up the motor speed to match the desired
speed. Once the request is removed the motor speed will
return to the fixed level. As with the traction control and
motors, the lift/steer control and motor have thermistors
for thermal protection and the motor has a built-in encoder
for speed feedback.
Section 1
Description
The CLARK GEX uses a Dual AC controller to control both drive motors and a single AC controller
to control the single motor/pump combination which supplies flow to all hydraulic functions and
steering.
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