Auxiliary (toad) braking systems
by Tom Jones
Most states in the U.S. and most provinces in Canada have requirements for towed vehicles to be equipped with auxilliary brakes. The requirement for a saftey mechanism in the event of a breakaway also varies by location. There are various options available to the motorhomer towing a car or other vehicle (hereafter called a "toad").
The following discusses a few proprietary systems, but these are intended as generic examples and no endorsement of a specific method or brand is implied. Several of the manufacturers claim that theirs is "the best" &/or "the only proportinal braking system".
The Brake Buddy employs a box that sits on the floor of the toad in front of the driver's seat. A lever is attached to the brake pedal and the box is plugged into a 12 volt receptacle. This system requires no permanent installation and is easy to use. However, it does require finding storage space for the box when you want to drive the toad.
There are alternative brands to Brake Buddy, some of which operate on the same principle and others which operate on a different principle. But, in each case, they employ a box on the floor of the toad and a lever hooked to the toad's brake pedal. The Blue Ox Apollo braking system is one such system.
Most of these 'box on the floor' systems offer an indicator that sits on the dash of the towing vehicle to alert the driver when the brake in the towed vehicle has been applied. Some of these indicators are activated by a signal from the brake box, while others such as the indicator for the Blue Ox Apollo are activated by the physical motion of the brake pedal in the towed vehicle. The latter is considered by some to be a more definite indication that the brakes on the towed vehicle have been applied.
All the 'box on the floor' systems have a breakaway option which uses a breakaway switch at the front of the toad connected to the coach with a stainless steel cable.
M & G Engineering air brake
The M&G system uses an air cylinder installed between the master brake cylinder and boost, located under the hood of the toad. It requires the installation of an air line from the air cylinder to a connector at the front of the toad. It also requires tapping into the air system on the coach and running an air line to a connector at the rear of the coach. Hookup and disconnect merely requires plugging in a flexible air hose between the coach and the toad.
M&G also produces variations of their system for coaches that do not have air brakes:
- For coaches with hydraulic brakes, a 12-volt air compressor, an air accumulator tank and a proportioning valve are mounted in the coach to provide the air necessary to operate the toad brakes.
- Coaches with air-over-hydraulic do not require the compressor.
A breakaway system uses a separate air reservoir and air diverter valve mounted under the hood of the toad and a breakaway switch mounted at the front of the toad. A stainless steel wire runs between the disconnect switch and the rear of the coach so that, if the toad breaks away from the coach, the breakaway switch is operated, diverting air from the reservoir to the air cylinder, thereby applying the toad brakes.
U.S. Gear Unified Tow Brake
The U.S. Gear system uses a power module, an electrical solenoid permanently mounted on the floor of the toad, and an arrangement of cable and pulley to activate the toad brakes. It also requires the installation of a vacuum pump under the hood of the toad. The system is connected via an umbilical cord and additional wiring to a controller on the dash of the coach.
A schematic of the components of the US Gear brake system can be viewed here
A breakaway switch is mounted at the front of the toad and connected to the coach via a stainless steel cable.
The SMI brake is a vacuum-assisted toad brake, available in various configurations. This system uses a vacuum pump connected to the toad's vacuum booster tank via a plastic "tee" inserted into the towed vehicle's vacuum line between the brake booster and the engine.
Air Force One
The Air Force One braking system, also manufactured by SMI, uses air from the coach to operate the toad brakes via a small actuator attached to the brake pedal. It also uses an air-driven vacuum generator to provide the boost function in the toad. No electrical power is required for this system to operate. Additionally, the system incorporates an automatic shutoff valve to prevent loss of coach air in the event of a breakaway
The Air Force One includes wiring from the car brake switch to a LED light that they mount on the tow bar to display brake engagement in the rear camera. This wire can be run to the m/h dash so that you have immediate indication of the toad brakes being on.
The Brakemaster by Roadmaster uses an actuator attached to the brake pedal. A unique feature of this system is that the actuator can be operated either by hydraulic or air, depending on the what braking system is on the coach.