Bar-assisted Trailer-backing

After spending awhile pondering an easy and safe way for a car or truck to push a trailer in reverse, I tested one method with a model made from Knex the construction toy and drew a schematic of the results. Instead of unstably pushing a trailer via its tongue, the tow vehicle pulls the trailer from its rear.

This is done by using a bar that becomes an extension of the car’s centerline. The bar is a part of the trailer’s understructure, connected to its back end with a flexible joint, but is held solidly by the hitch so it is always parallel to the tow vehicle’s direction when in reverse. This has the same positive effect as if an imaginary car facing the other way were behind the trailer, towing it.

While traveling forward, the usual hitch-trailer tongue would be used, but as soon as one starts backing up (noted in the electrical harness), the tongue coupler is released while the bar end is held fast by the modified hitch. When moving forward again, the bar is released after the tongue is again coupled.

Some difficulty arises upon change of direction when the two vehicles are at an angle to each other. This means that the trailer tongue must be pulled to the hitch, or the bar pulled into alignment with the car, hydraulically during the initial movement in the new direction forward or reverse, respectively. The forces needed seemed minor.