Electric drive system for industrial truck

Claim 1

IN A BATTERY DRIVEN INDUSTRIAL TRUCK, A MULTIPLE PHASE ALTERNATING CURRENT INDUCTION MOTOR, A PLURALITY OF POWER INVERTER CIRCUITS ENERGIZABLE BY THE BATTERY FOR PRODUCING ALTERNATING CURRENT IMPULSES AT THE CONSTANT AMPLITUDE OF THE BATTERY, TO ENERGIZE EACH PHASE OF THE MOTOR, FREQUENCY ADJUSTABLE OSCILLATOR MEANS PRODUCING A SERIES OF PHASE DISPLACED SIGNALS, ONE OF EACH PHASE OF THE MOTOR, AND CONTROLLING THE POWER INVERTER CIRCUITS TO PRODUCE THE ALTERNATING IMPULSES AT THE FREQUENCY OF THE OSCILLATOR MEANS, A PLURALITY OF ADJUSTABLE POWER REGULATOR CIRCUITS, WITH ONE FOR EACH PHASE OF THE MOTOR, FOR REGULATING THE DURATION OF THE CONSTANT AMPLITUDE ALTERNATING CURRENT IMPULSES FROM THE INVERTER CIRCUITS ENERGIZING EACH PHASE OF THE MOTOR, AND A SINGLE MANUAL CONTROL FOR ENABLING SIMULTANEOUS AND CONTINUOUS ADJUSTMENT OF THE OSCILLATOR MEANS TO CHANGE FREQUENCY, AND SIMULTANEOUS AND CONTINUOUS ADJUSTMENT OF THE PLURALITY OF POWER REGULATOR MEANS TO VARY THE POWER APPLIED TO THE MOTOR AT EACH FREQUENCY.