How do trailer brakes work?

Just like cars, trailers have braking systems that require periodic servicing. Inside a trailer’s braking system, you will either have disc or drum brakes (with disc brakes being the most common). pistons are used to push the brake shoe against the brake drum. This causes friction, allowing the trailer to slow down along with the vehicle it is attached to.


Different types of trailer brakes:

There are different types of trailer braking systems with two common ones being a mechanical system connected to the towbar coupling, that applies braking force to the trailer wheels when the vehicle slows down. This is the most common trailer braking system and is used on most mid to larger size tandem trailers.  They generally use disc brakes and pads to slow the trailer down.

Other more complex systems use a combination of electronics, electrical and mechanical control to more accurately apply your trailer brakes when required. These electronically controlled trailer braking systems are often used on larger trailers with heavy loads or expensive, or for caravans.

Causes of faulty trailer brakes:

Worn disc rotors / drums or brake shoes / pads — The brake disc rotors and brake pad lining can wear over time, reducing their effectiveness. Also if you have an older trailer with brake drums, the brake drum and brake shoe lining can wear over time, reducing their effectiveness.

Seized Brake Caliper or Wheel Cylinder –
trailers can often sit for long periods of time without being used. This is bad news for your trailer braking system as your brake fluid will tend to absorb water moister from the air over time. This water moister causes corrosion in your trailer disc brake calipers or drum brake wheel cylinders.

Disc calipers and wheel cylinders can also seize from the trailer being outside in the rain for too long. Rust builds up over time, which can lock the wheel cylinder or disc caliper in one position, either giving you no brakes, or having your brakes jammed fully on.

Trailer being used on or near the beach often have more brake problems due to the salt water and the corrosive salt in the air.

Fishing boat trailers are also prone to more brake related problems due to the harsh salt water conditions that must endure. Even fresh water boats have an increased level of brake related problems as well.

If you tow your trailer with your brakes partially stuck on, you are likely to destroy the majority of your trailer braking system.

Leaking wheel cylinders or disc brake calipers – your brake disc caliper or brake drum wheel cylinders internal piston seals can be destroyed and start leaking due to the water in the brake fluid causing corrosion as described above. Once this process starts your trailer may loose all of its brake fluid fairly quickly, meaning your trailer brakes will no longer work.

Electrical faults 
– On electronically / electrically controlled trailer braking systems wires are used to connect the trailer to your car. These wires send data signals to control things such as when and how hard to apply the brakes. A damaged wire can cause the brakes on your trailer to malfunction. Wires/connectors may become corroded, open or short circuited over time, damaging the connection.

Trailer Parking Brake left on while towing – sometime people bring us trailers where they have accidentally left the manual parking brake on the trailer while towing. The resulting friction has caused the brake pads / calipers  or brake shoes / drums to overheat and often this completely destroys the braking system.




Symptoms of faulty trailer brakes:

  • The trailer’s brake lights are not turning on.
  • The trailer isn’t braking as quickly or at all.
  • The trailer feels heavy to pull, and the brakes smell like they are burning



Trailer brake repair in Hamilton

Does your trailer’s braking system need repairing? If so, we can help you.

At Grimmer Motors, we can examine your trailer’s braking system, identifying any underlying faults. We can then replace the damaged components and get your trailer’s brakes working correctly again quickly.

For fast, quality trailer repairs, servicing and WoF in Hamilton, contact Grimmer Motors today!


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