Motrec E-242HD Operator And Maintenance Manual page 19

Maintenance
REVERSE ONLY
On a SEPEX motor control, check the forward signal input on the controller.
On a series wound motor control, a bad forward contactor is the most probable cause of the problem.
Switch to forward and check the voltage on the forward control wire. If not B+, replace the F/R switch.
If B+, turn off the key switch, disconnect batteries, disconnect power terminals on the F/R contactors,
check the resistance across N.C. power terminals of the forward contactor. If not 0 ohm, change the
forward contactor. If 0 ohms, switch to reverse and check the resistance across the reverse N.O. power
terminals. If not 0 ohms, change the reverse contactor.
TRAVEL AT REDUCED SPEED
Check batteries.
Turn off all switches and disconnect charger. Wear face shield and gloves. Do not disturb any
battery connection to avoid sparks. Check the specific gravity of each cell. Cold batteries,
highly discharged batteries or dead cells are the most frequent causes of reduced travel speed.
Check potentiometer.
Turn off the key switch, disconnect potentiometer terminals. Check the resistance between
terminals.
Other causes of lower speed:
dragging brakes;
cold temperature (higher differential oil viscosity).
INTERMITTENT OPERATION
A bad potentiometer is the most probable cause of the following:
acceleration is not constant;
maximum speed is erratic;
sudden stop after a bump or shock;
erratic starts, requiring several pedal cycles.
A bad F/R contactor is also a probable cause of the following:
sudden stop after a bump or shock;
would not start to move at times.
Erratic starts could also be the cause of a misadjusted potentiometer or micro-switch; the pot signal
must be less than 50 ohms when the micro-switch turns on.
PMC has an HPD safety feature that prevents the vehicle from moving if the accelerator pedal is
depressed before the key switch is ON and seat switch is activated.
PMC may also have an SRO safety feature that prevents the vehicle from moving if the F/R switch is
activated before turning on the key switch and activating the seat switch.
The vehicle stops on a steep and long ramp or while towing a heavy load: the circuit breaker has open
to prevent motor overheating and will reset automatically after one minute. The PMC is also equipped
with an internal thermal protection that cutback the current until the PMC has cooled down.
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