Reverse direction control for industrial truck - over-rides protection circuits to give rapid deceleration

摘要

With a fork-lift truck, the motor drive control thyristor can be regulated by pulses from a generator (G) whose frequency is determined by the action of a potentiometer (R) linked to the accelerator. The reversal of motor direction causes an inhibit circuit (H) to reduce the pulse frequency in order to prevent violent deceleration if the reversal occurs during motion. A switch (S/K) is incorporated to open-circuit the inhibit to prevent it acting upon the pulse generator. In this way, the driver can operate the switch in an emergency and produce fast braking. The switch can be mounted on the control handle-bar and operated by the driver's stomach if he backs into an obstacle.