Feedback failure protection for motor in crane control system

Claim 1

A CRANE CONTROL FOR CONTROLLING THE CURRENT TO A HOIST MOTOR BY CONTROLLING THE IMPEDANCE OF A LOWER AND RAISE SATURABLE REACTOR INCLUDING A D.-C. VOLTAGE SOURCE, A LOWER AMPLISTAT HAVING A TURN-ON CONTROL WINDING AND A GATE WINDING, THE GATE WINDING OF SAID LOWER AMPLISTAT CONNECTED TO THE LOWER REACTOR, A RAISE AMPLISTAT HAVING A FIRST AND A SECOND TURN-ON WINDING AND A GATE WINDING, THE GATE WINDING OF SAID RAISE AMPLISTAT CONNECTED TO THE RAISE REACTOR, A TACHOMETER FOR PRODUCING A VOLTAGE PROPORTIONAL TO THE SPEED OF THE HOIST MOTOR, MEANS CONNECTING SAID TACHMETER OF THE FIRST TURN-ON WINDING OF SAID RAISE AMPLISTAT AND TO THE TURN-ON CONTROL WINDING OF SAID LOWER AMPLISTAT, A FIRST POTENTIOMETER HAVING A MOVABLE CONTACT, MEANS CONNECTING THE TURN-ON CONTROL WINDING OF SAID LOWER AMPLISTAT AND THE FIRST TURN-ON CONTROL WINGING OF SAID RAISE AMPLISTAT TO THE MOVABLE CONTROL OF SAID FIRST POTENTIOMETER, A SECOND POTENTIOMETER HAVING A MOVABLE CONTACT, MEANS CONNECTING SAID TACHOMETER TO THE MOVABLE CONTACT OF SAID SECOND POTENTIOMETER, MEANS CONNECTING SAID FIRST AND SECOND POTENTIOMETERS TO SAID D.-C. VOLTAGES SOURCE, SWITCHING MEANS FOR MOVING THE MOVABLE CONTACTS OF SAID FIRST AND SECOND POTENTIOMETERS TO LOWER THE IMPEDANCE IN SAID LOWER AND RAISE REACTORS TO CONTROL THE CURRENT TO THE HOIST MOTOR, AND MEANS FOR CONSTANTLY CONNECTING THE SECOND TURN-ON CONTROL WINDING OF SAID RAISE AMPLISTAT TO SAID D-.C. VOLTAGE SOURCE TO LOWER THE IMPEDANCE OF THE RAISE REACTOR AND ALLOW CURRENT FLOW TO THE HOIST MOTOR.