When the tow vehicle’s brakes are applied, an electric current is sent from the brake controller to the trailer brakes. The electromagnets on the brakes are energized and attracted to the armature surface of the drums. This moves the actuating lever in the direction of the drum rotation.
The resulting force causes the primary shoe to be pushed out against the inside of the drum. The movement of the primary shoe in the direction of drum rotation forces the secondary shoe out against the drum, providing full braking capability.
Manual electric brakes typically should be adjusted:
- After the first 200 miles of operation when the brake shoes and drums have “seated”
- At 3,000 mile intervals, or
- Under special operating circumstances, i.e. heavy use, frequent stops, or variable terrain
The use of self-adjust brakes virtually eliminates the need for manual adjustments.
With the brake magnet at the bottom of the brake, the magnet actuating arm will curve either to the left (LH) or right (RH) from the top pivot point of the brake arm down to the magnet. If the arm curves to the left, it is a left-hand brake. If it curves to the right, it is a right-hand brake.
In addition, the primary shoe is always to the front of the trailer and the brake wires always exit the rear of the brake backing plate.
Self-adjust electric brakes automatically rotate the brake adjuster every time there is a brake application that closes the gap between the brake shoe and the drum caused by lining wear.
Self-adjust brakes save the trailer owner the time and expense of required manual brake adjustments. Proper adjustment leads to better efficiency from the trailer brakes; therefore, the wear on the tow vehicle brakes is greatly reduced. Most importantly, properly adjusted trailer brakes can greatly reduce the required stopping distance.
CSA stands for Canadian Standards Association. Because there are no uniform standards for trailer brakes in the USA, many brake manufacturers use CSA certification to show their products meet certain performance specifications.
CSA certification is required to sell trailer brakes and trailers into the Canadian market. Where required, all Dexter, Red Onyx, and Trailer Parts Pro brands are CSA approved.