What part of a trailer attaches to the ball hitch on a towing vehicle?

The part of a trailer that attaches to the ball hitch on a towing vehicle is called the coupler. The coupler is specifically designed to fit over the hitch ball, creating a secure connection between the trailer and the towing vehicle. This allows for safe towing as it helps to ensure that the trailer remains attached during transportation.

Understanding how the coupler functions is important for safe trailer operation, as it provides not only the connection point but also often incorporates mechanisms to lock the coupler onto the hitch ball, preventing unintentional detachment.

The other parts mentioned serve different purposes; the dolly wheel is typically used for maneuvering the trailer when it is detached from the vehicle, the winch is used for lifting or pulling loads onto the trailer, and the brake system is crucial for stopping the trailer but does not play a role in the attachment of the trailer to the towing vehicle.