Equipment trailer brake mis-adjustments and failures can dramatically increase stopping distances, resulting in increased chance of collisions or loss of control. Properly maintaining your trailer brakes and testing their function prior to hitting the road will help alleviate risks from potential failures.
“All brakes should be tested each time you use the trailer by applying them manually if possible (electric and air) at low speed to make sure that you feel them applying,” says Scott Brown, warranty coordinator, Felling Trailers, Inc. “If applying the brakes manually is not an option, you should perform a couple of low-speed brake applications to make sure you feel the brakes apply.”
Annual inspections are also recommended. “A visual inspection of the brake system periodically (once a year or every 12,000 miles) will go a long way in preventing downtime or sitting alongside the road,” Brown points out.
Also take into consideration outside influences, such as the weather conditions. The region where you operate can definitely impact performance, especially cold weather climates where temperatures drop below freezing. In these climates, the brake shoes can actually freeze to the drum.
“In cold weather, brakes can freeze to the drum and not release,” Brown elaborates. “We see this a lot with air brakes as they are applied as a parking brake when the trailer is not being used. When pulling out, you should try to make sure all the wheels are turning. You may feel that the trailer seems to be pulling hard. If you do find that a brake is frozen, you can typically get it to release by tapping on the drum with a hammer. If you are still unable to get the brake to release, you may need to pull the brake apart to clean the ice out of the drum, but typically the hammer will take care of it.”
Chemicals used in cold weather climates can also pose a challenge. “In cold weather areas where salt/chloride are used on the roads, it is very important to make sure that the brakes are sprayed off to try to flush the chemical out of the brakes,” Brown emphasizes. “If the brakes are washed out and the temperature falls below freezing, it is a good idea to park the trailer in a warm building to give the brakes a chance to dry off before parking it back outside.”
In addition, trailers that sit for prolonged periods may be impacted by corrosion. “Trailers sitting can cause issues with the braking system,” says Brown. “They will start to rust, which causes issues with the parts working freely. If a trailer sits for a while with no use, I have heard of some people who will pull the trailer down the road and apply the brakes just to make sure everything continues to move.”
When it comes to maintenance and troubleshooting, there are different considerations for each type of braking system currently used — air, hydraulic and electric. One constant is you want to ensure that the brake shoes, or pads in the case of disc brake systems, have sufficient material thickness and the brake drum, or disc, is smooth and still within specification.
Air Brakes Must Be Properly Adjusted
Failures in air brake systems can be caused by several factors, including air reservoir failure, faulty spring brake control valves, restricted/pinched trailer service air line and pressure protection valves sticking due to corrosion.
“Always perform a pre-trip inspection prior to travel,” advises Josh Doyle, customer service manager at XL Specialized Trailers. “Air leaks can be heard rather easily by operating the air valves.”
It is important to keep the system clean. “Corrosive environments — climates with excessive rain, salt in the air and snow — can seize up brake pads. Routine trailer cleaning during winter months is recommended. This includes power washing the trailer.”
Pay careful attention to slack adjusters. “Improperly adjusted and improperly maintained slack adjusters can cause brake issues,” says Doyle. “Refer to the slack adjuster manual for instructions on how to properly care for them. For example, keeping slack adjusters greased is important. Also, allowing self-adjusting slack adjusters some time to self-adjust can help in the long run.”
Make sure trailer brakes are correctly adjusted and working properly. “Set trailer brakes and observe brake pads and slack settings,” says Doyle. “The easiest way is to watch the slack adjusters extend and retract in order to ensure the brakes are functioning. Refer to the slack adjuster manual if you see excessive wear or a need for adjustments.”
If your trailers spend a significant amount of time in the yard, you should take extra precautions. “Quarterly operation checks on the trailer are recommended,” says Doyle. “Simply hooking the trailer up and pulling it around the yard can eliminate brake lock-ups and air operation issues.”
To maximize uptime, don’t overlook inspections and maintenance. “Consistent inspections, once a week, and routine maintenance are recommended along with the mandated yearly federal inspections,” Doyle notes.
Electric Brake Systems Need Good Connections
Electric brakes use electromagnets to actuate the drum brakes. You control the electricity to the brakes with the brake controller in the cab of the tow vehicle and the brake light circuit on your vehicle. Trailer brake controllers differ in the number of brakes they can control. Make sure you are using a compatible brake controller.
If these systems are not working, there are several possible culprits, from poor electrical connections to frozen or worn out components. “Always check the plug first, confirm that there is power coming from the truck and that the trailer plug is free of corrosion and fits firmly into the plug on the tow unit,” says Brown. “If the trailer has sat for a while, the armature can start to rust and/or the lining surface on the drum will rust. Sometimes just low-speed braking before leaving will clean things up, or you might need to pull the drum off to clean things and lubricate the armature arm.”
The electromagnet that activates these brakes is also subject to wear. During routine inspections check the wear indicators of the electromagnets to make sure they are in good service.
“Most brakes now are self-adjusting and only need to be checked once a year. But if you have an older trailer, it is recommended that the brakes are manually adjusted every 3,000 miles,” notes Brown.
Hydraulic Brakes Rely on Clean Fluid
One of the more common hydraulic brake systems for equipment trailers are surge brakes. They use the momentum of the trailer to actuate the brakes.
When you activate the brakes in the tow vehicle, the trailer presses against the trailer hitch and activates the hydraulic master cylinder in the trailer hitch and sends brake fluid to the trailer brakes. The more you slow down the vehicle, the more pressure on the master cylinder in the trailer hitch and the harder the trailer brakes are applied. When going downhill, there is steady pressure applied to the master cylinder in the trailer hitch that ensures the trailer brakes and the brake system keeps the trailer’s speed in check.
There is a very small restrictor orifice built into the surge brake system to slow the hydraulic fluid and keep the trailer brakes from pulsing on and off as the trailer hitch loads and unloads as it is being pulled down the road. Due to the very small orifice opening, it is important to keep the brake fluid in surge brake systems clean.
If a surge brake system doesn’t work, first remove the master cylinder cap and make sure there is brake fluid in the reservoir. If there isn’t any fluid, you may consider rebuilding or replacing the master cylinder and wheel cylinders. Don’t just add brake fluid and go back to work. You must find the source of the leak.
If the system has the proper amount of brake fluid, check the condition of the brake shoes and make sure they are adjusted properly. Then check that the restrictor orifice is not clogged, the master cylinder is pumping and the wheel cylinder is not frozen. You also need to check that there is no air in the system by properly bleeding the fluid lines.
Another type of brake system is the electric/hydraulic trailer brake. It receives electric signals from the tow vehicle’s brake controller and applies pressure to the trailer’s hydraulic brake lines.
These systems can be either drum or disc brakes. An electric-over-hydraulic brake actuator on the trailer receives electric signals from the tow vehicle’s brake controller and applies pressure to the trailer’s hydraulic brake lines. The systems typically utilize a breakaway battery on the trailer that needs to be functional for proper system operation.
When there is a problem with these systems, most of the time it is some type of wiring issue such as a loose connection or weak ground. The other likely culprit is that the brake controller is either not in electric-over-hydraulic mode or the controller is not electric-over-hydraulic compatible. This is the case with most factory integrated brake controllers.
Preventing many issues simply boils down to maintenance. “Hydraulic brakes are relatively trouble free,” Brown comments. “However, they should also be taken apart and inspected once a year or every 12,000 miles.”