Abstract: A semitrailer cargo door locking system is described for use with a semitrailer cargo door having as part of its opening mechanism a rotatable handle which secured within a hasp mechanism comprising a rigid lower hasp and a swivelable upper hasp. The locking system includes a shackleless keyed lock having an internal bolt for engaging aligned holes provided in the upper and lower hasps, thereby preventing unauthorized opening of the cargo doors when in a locked state. The lock housing is provided both with a protective extension to minimize attempts to pry the lock, and with a tapered side wall to prevent removal by the application of a destructive torque applied by a wrench or other like device. The lock is further provided with a anchor line for either permanently or removably securing the lock to the cargo door. To provide the lock with the ability to be used with regulated loads, a means may also be provided to attach a sealing structure to the lock.

Abstract: A semitrailer antitheft system is described for use with a semitrailer landing gear of the type having a housing-enclosed gear train coupled to a telescoping lower strut. The antitheft system includes a non-rotatable shaft-mounted gear segment for engaging the gear on the stationary shaft of the existing gear train, thereby preventing unauthorized raising or lowering of the telescoping lower strut. A lock is provided on one end of the non-rotatable shaft to prevent unauthorized disengagement of the gear segment from the gear train. The antitheft system may be incorporated into an existing housing, if room permits, or the housing may be modified so as to provide for incorporation. Alternatively, the antitheft system may be provided as an add-on kit to be attached to the existing housing.

Abstract: A security door-locking system is described for locking closed doors of tractor cabs on truck tractors, for example, of the type used to pull over-the-road common truck trailers, and vehicles, etc., with similar pre-existing door latching systems. A flat rigid bar has a hole near one end for fitting over the striker pin on the door jamb; and the other end of the bar may be attached to a lock outside the tractor cab after the door is closed. A retainer between the lock and the door/door-jamb provides a secure locking arrangement. And a system like a ratchet provides for attaching the lock to the bar in a tight position with the door.