How are Disc Brakes Operated on Trailers or Vehicles That are Being Flat Towed

Updated 04/06/2011 | Published 04/05/2011

Products Featured in This Question

Kodiak Disc Brake Assembly - 10" Hub/Rotor - 5 on 4-1/2 - Dacromet - 3,500 lbs

(26)

$259.48

Dexter DX7.5 Drop-N-Go Brake Actuator - Disc Brakes - 2" Ball - Zinc Plated - 7,500 lbs

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$404.81

Roadmaster Even Brake Portable Flat Tow Brake System - Proportional

(57)

$1930.00

Dexter BrakeRite II Electric Over Hydraulic Actuator Kit - Vented - 1,500 psi

(38)

$1227.68

Question:

How are disc brakes on trailers operated. Do they have to have hydralics connected to the tow vehicle or can they be operated by electric as the other trailer brake do? Could a extra caliper be placed on the vehicle being toweds back brake that would brake the car with electric power from the front vehicle? Could this work on a trailer also?

asked by: William A

Expert Reply:

Disc brakes on a trailer are operated by a hydraulic brake actuator like the Dexter Brake Actuator, part # 099-175-20, that is installed on the tongue of the trailer. It is called surge braking because it uses the surging of the trailer toward the tow vehicle to operate the hydraulics on the disc brake system.

The surge or push of the trailer toward the tow vehicle during deceleration automatically synchronizes these trailer brakes with the tow vehicle brakes. As the trailer pushes against the vehicle, the actuator telescopes together and applies force to its master cylinder, supplying hydraulic pressure to the trailer's brakes.

I am including a link to the instructions on a Titan hydraulic brake actuator. It will describe how the surge braking system works.

The other system that can be used on a trailer with disc brakes is the electric over hydraulic braking system like the Titan BrakeRite EHB Electric-Hydraulic Actuator, part # T4813102. This braking system uses a pump and motor controlled by a electric brake controller in the tow vehicle. The trailer brakes are applied when you apply the brakes in the tow vehicle. This system increases response time compared to the regular hydraulic brake actuator on the trailer tongue. I am including a link to the instructions on the Titan BrakeRite system.

On a vehicle that is being towed you would use the Roadmaster Even Brake Portable Proportional Braking System, part # RM-9400. This system engages the towed vehicle brakes proportionally to how much the towing vehicle is braking, reducing wear of both vehicles brakes. It sits in front of the towed vehicles drivers seat and will operate the brake pedal of the towed vehicle by the electrical system of the tow vehicle.

These are the best systems that are used to operate the disc brakes on a trailer or towed vehicle. I do not know about attaching another disc brake caliper to a towed vehicle or trailer and have it operate the brakes. I would not have anything that would allow you to do that.