59
- FORM NO. 56043115 - 34 RST
Wheel Drive System
Wheel Drive System
Functional Overview
See Figures 1 and 2.
A 375 watt (0.5 HP) permanent magnet (36V) motor transaxle
(M1)
is used for the wheel
drive on all machines. A Curtis PMC solid state speed controller
(A2)
regulates the variable speed and Fwd/Rev
wheel drive motor functions. The controller is located in the rear electrical compartment (accessible by removing the
six screws securing the top main control panel). Two palm drive buttons, wired in parallel, actuate the transaxle
drive motor. A reverse button controls the machine reverse. A speed limit pot R1 (knob adjusted) mounted in the
handle regulates the machine’s maximum transport and scrub speeds.
Drive Motor System Function
See Figures 2 and 3.
With the key switch S3 closed the Brn wire inputs 36V to the A2 speed controller (Pin
5-KSI) to make its internal control circuits operational (powering it up). The F3 circuit breaker (30 amp) supplies
the positive load circuit voltage input to the B+ controller terminal (Wht/Yel wire). The black wire from the battery
negative standoff supplies the (NEG.) input to the B- controller terminal.
Pressing either palm drive switch (S6 or S7) activates the operator input to the speed control which generates the
internal voltage signals (0-5volts) needed for the controller’s output operation. These control board voltage input
signals are what energizes the Fwd and Rev directional relays, which then selects the motor polarity and final
voltage level outputs at the M1 and M2 terminals.
When the operator turns the R1 speed limit Pot from min. to max. (clockwise) this causes an input resistance
relationship change between the pot high (+) and wiper terminals (high to low ohms) thus increasing the maximum
wheel motor operating speed range. Turning the knob (counterclockwise) increases the resistance and the motor
speed range is reduced.
FIGURE 1
