Automobiles and trucks are commonly fitted with towing hitches to allow them to pull trailers of assorted types. The trailers may support boats, off road vehicles, or campers, or may be for transport of industrial or home equipment. In any event, the value of the trailer and the towed goods can be considerable, presenting an attractive target for thieves. However, because of the large size of the automobile-trailer assembly, it must at times be parked outside and will occasionally be left unattended. Automobiles are provided with numerous well known impediments to theft, i.e.: door locks, ignition locks, alarms, etc. To prevent the trailer from being separated from the hitch, the coupler arm of the trailer is typically locked to the hitch ball which is supported on the vehicle towing hitch.
The hitch ball may be attached directly to an attaching member of the pulling vehicle which may be the bumper of the pulling vehicle or a special extending tongue that is affixed to the bumper or underbody of the vehicle. The hitch ball has a spherical upper section with a downwardly protruding threaded shaft which extends through the vehicle hitch. Because different trailers require hitch balls of different diameter, for example from 1-7/8 to 2-5/8, the hitch ball must be separable from the vehicle hitch. The shaft of the hitch ball is held in place by a nut threaded beneath the tongue or the bumper of the vehicle. The towed vehicle trailer arm has a cup or socket which fits over the hitch ball and allows a pivoting and rotating connection between the trailer and the vehicle. The trailer arm will typically have structure which allows it to be secured and locked to the hitch ball.
While trailer hitch socket couplers are commonly permanently attached to the trailer, hitch ball couplers are specifically designed so that a hitch ball can be quickly and easily removed and replaced by a hitch-ball of the correct size to properly fit a trailer hitch socket coupler with a different sized socket. Thieves, too, often readily exploit these hitch ball coupler design features and in a matter of minutes can remove the hitch ball still clamped and locked into place to the trailer and reposition the hitch ball shaft in a hitch on a vehicle under their control, making it possible to rapidly drive off with the trailer and its contents.
To prevent the hitch ball from being separated from the towing vehicle hitch, it has heretofore been necessary to in some way lock the hitch ball independently, for example by a padlock inserted through the shaft beneath the hitch tongue. Not only does an additional lock add to the cost of the towing assembly, it represents an inconvenience to the driver, who must carry an additional key and take the additional time required to unlock the hitch ball lock each time the hitch ball is separated from the towing vehicle hitch.
An unlocked hitch ball not only accommodates thieves, it also presents the possibility that the securing nut may work its way off the shaft, leading to accidental disconnection while travelling. Oftentimes, additional coupling devices such as chains or secondary clamping devices and locks are employed to prevent accidental disconnection.
A trailer which is parked without a hitch ball received within the trailer arm is also susceptible to being mounted on a hitch ball or other protrusion from a towing vehicle and being removed by thieves. To prevent the trailer and from being used in this manner, hitch balls without protruding shanks, such as those sold under the name TRAILER COP have been employed. Such a device fills the cavity in a trailer arm and prevents insertion of any supporting element. However, the hitch ball without a shaft must be removed and replaced with a hitch ball with a shaft when it is desired to connect the trailer to a towing vehicle.
What is needed is a hitch ball that is relatively simple, inexpensive, easy to manufacture, and which is securable to the towing vehicle and trailer without the requirement of a separate lock.