Abstract: An anti-theft lock structure for a vehicle having a code box which must be accessed to enable the vehicle to operate. When the vehicle is not enabled the steering column is locked in position, the gear shift lever is locked in position so the transmission cannot change gears, the front brakes are locked and the rear brakes are separately locked; and the electrical system, for a gas engine is disabled at the distributor, and the fuel system, for a diesel engine, is disabled at the fuel cell. The lock has a piston slidably received in a hydraulic cylinder having a piston rod extending from the piston to an operative shaft. An electromagnet is supported on the hydraulic cylinder and adjacent to the piston so that the field from the electromagnet holds the piston rod out of engagement with the operative shaft when the ignition of the engine is turned on. The engine has an oil system connected to the hydraulic cylinder to force the magnetic piston away from the gear rim when the engine has started.

Abstract: A shaft lock for an automobile with a steering column. The steering column has a gear rim thereon with teeth on its periphery and a hollow cylinder is attached to the car body. A magnetic piston is slidably received in a hydraulic cylinder having a piston rod extending from the magnetic piston to the gear rim. An electromagnet is supported on the hydraulic cylinder and adjacent to the magnetic piston so that the field from the electromagnet holds the piston rod teeth out of engagement with the teeth on the gear rim when the ignition of the motor is turned on. The motor has an oil system connected to the hydraulic cylinder to force the magnetic piston away from the gear rim when the motor has started. A helical compression spring is supported on the hydraulic cylinder which urges the magnetic piston from the gear rim and disengages the teeth on the piston rod from the teeth on the gear rim.