Abstract: A locking device for obstructing towing of an unattached trailer has a lock base and a single-armed curved interlock bracket. The lock base has a cylindrical leg. The single-armed interlock bracket has an grooved arm sliding along an aperture on the cylindrical leg and may be permanently attached to the lock base. Grooves on the arm allows a locking means to be engaged with the lock bracket at different height. When engaged, the locking means may restrict the interlock bracket from swirling. The open end of the interlock bracket provides flexibility to accommodate trailer couplers with different cap/rim sizes. The cylindrical leg may have a sealed bottom end and may function as a handle. The locking device may also feature a push-in locking mechanism to lock the interlock bracket in a position without using a key.

Abstract: A locking device for obstructing towing of a trailer has a lock base and a lock bracket. The lock base has an upright ball-shaped member and two legs each with an aperture. The lock bracket has two arms. When the locking device is in a locked condition, both arms are engaged in their corresponding apertures. When the locking device is in an unlocked condition, one arm of the lock bracket remains attached to its corresponding aperture, and the other arm is removed from the other aperture to release the coupler. Grooves on one of the arms allow a locking means to engage with the lock bracket at different height. In another aspect of the invention, the ball member is detachable and can be replaced by different sized ball member so that the same locking device can be used on trailer couplers with different socket sizes.

Abstract: A locking device for obstructing towing of an unattached trailer has a lock base and a single-armed curved interlock bracket. The lock base has a cylindrical leg. The single-armed interlock bracket has an grooved arm sliding along an aperture on the cylindrical leg and may be permanently attached to the lock base. Grooves on the arm allows a locking means to be engaged with the lock bracket at different height. When engaged, the locking means may restrict the interlock bracket from swirling. The open end of the interlock bracket provides flexibility to accommodate trailer couplers with different cap/rim sizes. The cylindrical leg may have a sealed bottom end and may function as a handle. The locking device may also feature a push-in locking mechanism to lock the interlock bracket in a position without using a key.