Specifications

COIL DRIVER MODULES - these drivers are internal to the control card. They are the power

devices that operate F, R, lA, D, FW, RB, and PS contactor coils. These drivers open or close these

coils on command from the control card. All modules are equipped with reverse battery protection in

that if the battery is connected incorrectly, none of the contactors controlled can be closed electri-

cally.

lA THERMAL HOLD OFF - this feature prevents the lA contactor from closing when the truck is

in severe thermal cutback to avoid torque jumps. When the control goes into severe cutback, the

must pulse to time will inhibit the lA timer.

MUST PULSE TO TIME - this feature prevents the lA timer from timing if the oscillation pulse rate

has not reached a particular level of operation.

PULSE MONITOR TRIP ( PMT ) - This feature contains three features which shuts down or locks

out control operation if fault conditions exist that would allow uncontrolled ( run away ) speed of the

vehicle:

Look ahead

Look again

Automatic look again and reset

The PMT circuit will not allow the control to start under the following conditions:

1. If 1REC is shorted or if 1A contactor is welded, the control will not allow the F or R

contactor to close.

2. Will not allow the control to operate if F and R internal coil drivers are shorted or if

3REC diode is shorted.

The PMT circuit will shut down operation of the control ( opening of the F or R contactor ) under the

following conditions:

If 1REC fails to commutate ( shut off ), or if 1A power tips remain closed when they should be open.

After opening the F or R contactor the PMT circuit will check for a fault and if none is found will

reclose the directional contactor. If the fault still exist, the directional contactor will open and remain

open.

If 1A closes before a second commutation failure, the look again counter will automatically reset.

This eliminates the inconvenience of resetting the PMT with the key switch if the trip is due to ran-

dom noise.

When the PMT circuit prevents F or R contactors from closing, the PMT circuit can be reset only by

opening the key switch.

THERMAL PROTECTOR - (TP) - this temperature sensitive device is mounted on the lREC heat

sink. If the lREC temperature begins to exceed the design limits, the thermal protector will lower the