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What Are Trailer Axle Brakes?

Lori Kilchermann
Lori Kilchermann

Trailer axle brakes are placed on the axle of a trailer to assist in stopping the trailer when loaded. When attempting to slow or stop a trailer equipped with trailer axle brakes, an electric brake switch mounted inside of the passenger compartment of the towing vehicle activates the electric braking components on the trailer axle. This allows the trailer to be slowed or stopped suddenly without jackknifing or wrecking the tow vehicle. As the trailer axle brakes engage, the trailer is slowed to a straight and manageable stop, which allows the tow vehicle to remain in control and comfortably negotiate corners, traffic conditions and other road hazards.

There are two basic types of trailer axle brake controllers: proportional and time-delayed. The proportional controller senses the amount of braking that the tow vehicle is applying and applies the same amount of brake to the trailer axles. The time-delayed controller applies a minimal amount of brake when it senses the tow vehicle driver is applying the brakes. The trailer brakes are then slowly increased until the trailer comes to a stop. The amount of initial braking force, as well as the length of the delay, is custom set in the vehicle to function at a predetermined rate as selected by the owner.

Woman holding a book
Woman holding a book

The electric braking system used on trailer axle brakes is often accompanied by a manual surge brake that operates by the movement of the trailer tongue and hitch. In this type of trailer axle brake, the brakes are applied to the trailer wheels when the trailer begins to push or surge against the tow vehicle. The trailer's hitch is hinged to move back and forth as the trailer surges toward the tow vehicle. When the trailer moves ahead, the hitch moves back and pushes against a master cylinder that applies pressure to the trailer axle brakes. This system functions exactly like the brakes in the tow vehicle, except the brakes are activated by the surging of the trailer instead of the driver's foot on the brake pedal.

This surge brake system is occasionally used as the solitary brake system on the trailer, or an electric braking system may be used as an auxiliary system in conjunction with the hydraulic surge trailer axle brakes. The benefit of the hydraulic trailer axle brakes is that there are no electrical components to become corroded or disconnected. Regardless of the type or design of the trailer axle brakes, the trailer is less prone to sliding out of control or pushing the tow vehicle out of control when equipped with a braking system.

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