A trailer is an unpowered vehicle that is generally pulled or towed by a powered vehicle. A trailer may be an enclosed toy trailer, a mobile home, a travel trailer, a recreational vehicle, or any other unpowered single or multi-axel vehicle that is towed by a powered/towing vehicle. A trailer hitch, a fifth wheel coupling, or other type of tow hitch is needed to connect a trailer to the towing vehicle to draw the trailer with the towing vehicle, which can be, for example, a car, a truck, or other traction engine. A trailer is typically coupled to a towing vehicle by a ball socket, but may be coupled in some other fashion. Trailers may be coupled in a number of ways to the towing vehicle including by a drawbar or a tow bar.
When a towing vehicle pulls a trailer, external forces may cause the trailer to sway in either one direction or multiple directions. Trailer sway is a fishtailing motion of the trailer, which is caused by external forces that set the trailer's mass into lateral motion with the ball socket serving as the axis or pivot point. The motion can be described as a sideways seesaw. Typically, trailers sway in response to a high towing speed, swerving movement of the towing vehicle, gusting winds, bad roads, downhill travel, poor trailer design, poor weight distribution, or a bow wave of a large semi-truck, a box truck, or a van overtaking the trailer from the rear. Some trailers are designed for correction by the driver and will quickly re-stabilize. However, some trailers will continue to sway after the force that caused the instability has ceased. In fact, in some trailers, the sway motion may increase until control of both the towing vehicle and the trailer is lost. Unfortunately, many trailers are prone to sway due to poor weight distribution.
Trailer sway is an inevitable part of trailer towing which can be mitigated using a number of mitigation techniques. One such mitigation technique is to brake the trailer independently of the towing vehicle. When the speed of a trailer is reduced independent of its towing vehicle, tension is created between the vehicle and the trailer, which helps to stabilize the system. However, there remains a need for a cost-effective, reliable trailer sway mitigation device which would initiate braking of a trailer, thereby alleviating driver hesitations that trailer sway could initiate a dangerous condition for those aboard the towing vehicle and trailer combination.