Brake and Bearing Service
A very important and often overlooked aspect of trailer maintenance is the undercarriage – including axles, brakes, bearings, suspension, stabilizing jacks, tongue jacks and RV batteries. If the battery is dead, or the tongue jack is stripped, you notice. The axles, bearings, brakes, and suspension, however, are easily missed, as they are behind the tires and rims and go unnoticed unless the wheels are removed. Most trailer brakes have drum brakes; disc brakes exist but are only found on high end trailers and some boat trailers. We will focus here on electric drum brakes.
Let’s start with some background on drum brakes. Bolted on each end of the axle is a backing plate which has the brake shoes, adjusters, return springs, and magnets all as a complete unit. The hub drum is installed over top of the backing plate, the magnet and the shoes. When you apply the brakes on the tow vehicle an electric charge energizes the magnets, they grab onto the steel drum and the rotation of the drum will pull the magnet forward, applying the brakes. When the brake pedal is released the magnet de- energizes and relaxes the tension on the brakes. Another part of the inner working of the axle are the bearings. The bearings are installed inside the hub drum and slide over a polished steel spindle, supporting the weight of the trailer on the rims and tires. All these components are serviceable parts.
During an axle service, or brake and bearing service, a few different things happen. The tires get taken off and the hub drum gets removed, exposing all these components for the technician to inspect. A typical brake and bearing service should happen every year (two years maximum) or 10,000-15,000 Km of driving. Most trailers don’t have an odometer to track distance, so it’s a good idea to review all the trips your RV takes in a year and add that up.
One of the things that wears down your brakes and bearings is heat. There are many different sources from which this heat originates: the friction of the turning bearing, consistent braking, hot pavement, and more. This heat will do two things: 1) it will degrade the grease protecting the bearings; 2) it will crack the brake shoes.
Proper axle grease will withstand the heat of driving but like engine oil it needs to be changed at regular intervals. Getting a proper bearing service done will wash out the old grease, inspect the bearing and, if the bearing doesn’t need changing, will be repacked with new grease. If the bearings are heat checked or pitted, they need to be replaced.
Make sure to do your safety checks while making scheduled stops for fuel, lunch, etc. during your travels. To do this, walk to the trailer and put your hand on the rims – if possible, touch the center of the rim – it should be warm to the touch but if the center cap is so hot you can’t touch it, that indicates a problem. A dragging brake shoe or bad bearing can cause a lot of damage and be very expensive to repair. Brakes, like bearings, can be damaged by overheating which causes cracks on the shoe itself. If it falls apart while driving, the pieces can do internal damage to the drum.
The suspension assembly is another serviceable component of the trailer and can be done at the same time as a brake and bearing service. The suspension consists of the springs, equalizers, shackles, bolts, bushings, and if equipped, shocks. With the weight of the trailer and the torque produced on the suspension from turning, these parts will wear out over time. Remember, always check the tires for full pressure and uneven wear before your trip too.
As always, if you have any questions about this or any other RV towing, vehicle solutions, or truck accessories, send us an email email@example.com or give us a call 604.792.3132. We’re happy to help!