Section 8. Wire Guidance Toyota Orderpicker Model 7BPUE15 Service Manual

Theory of Operation

The steer controller monitors the direction of travel (forward and reverse) by monitoring the travel speed encoder. This encoder is mounted on top of the drive motor and turns with the armature shaft. As the encoder turns, it sends two voltages, SPEEDFB A and SPEEDFB B, to the steer controller. SPEEDFB A and SPEEDFB B will change state from approximately 12 volts to 0 volts and back as the encoder is rotated.

SPEEDFB A changing state before SPEEDFB B indicates one direction of travel. SPEEDFB B changing state before SPEEDFB A indicates the opposite direction of travel.

The steer controller must monitor both travel directions to keep the truck on the guide wire. The steer request for a truck traveling tractor - first is opposite to the steer request when the truck travels forks-first. The steer controller reverses the steer request as the travel direction changes.

The travel speed encoder also indicates the travel speed to the steer controller. The steer controller monitors the speed to allow smooth steering changes at all travel speeds.