A brake axle is found on a trailer. It contains a braking system that is typically magnetic or electric. This allows the trailer to apply its own brakes when assisting the tow vehicle in bringing the trailer to a controlled stop. This type of braking system is also activated by a wire, which engages the trailer brakes in the event the trailer becomes unhooked from the tow vehicle.
When pulling a trailer without a brake axle, the trailer can become difficult to control under emergency braking conditions. The trailer will sway and will often jackknife if the tow vehicle is forced to fully engage its brakes. The brake axle will apply braking to the trailer in such instances and often prevent the wild and erratic movement of the trailer.
On trailers with more than one axle, the brake axle will be placed in the froward axle in most instances. This is due to the loaded trailer having the greatest percentage of weight on the forward-most axle. A brake axle placed in the rear could cause the tire to skid under duress braking conditions, rendering the brakes useless. Higher-end trailers may have all axles equipped with brakes.
On an electric brake-equipped trailer, the tow vehicle must have a brake activation switch wired into its braking system. This switch will usually be installed under the dash of the tow vehicle and will have lights to signal when the trailer brakes are being applied. This switch will also have a manual override lever that allows the operator to apply the trailer brakes independently of the tow vehicle's braking system.
One added benefit of a brake axle on a trailer is its ability to apply the brakes and stop the trailer in the event of it coming loose from the tow vehicle. A wire, hooked between the trailer and the tow vehicle, will pull the brakes on should the trailer come loose from the tow hitch. This will stop the trailer and prevent it from rolling uncontrolled a great distance down the road.
Brake axle maintenance is relatively easy with only minimal parts involved. A good visual inspection and seasonal wheel bearing greasing is typically all that is required to keep the brake axle in good condition. An occasional application of the trailer braking system is encouraged to keep all of the parts in top operational condition. With the trailer empty, apply the brakes suddenly and check to ensure the trailer brakes engage.