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Old 04-02-2005, 09:34 PM
RockyMtnRay RockyMtnRay is offline
Join Date: Jul 2001
Location: Colorado Springs, CO
Posts: 823
Default How do they work? Which ones are dangerous?

The ideal goal for a brake controller is to provide trailer braking that's completely proportional to how hard you are braking the tow vehicle, and to do it under all conditions. As you will see below, some controllers (the expensive ones) achieve this ideal; the very inexpensive ones don't even come close.

There are 4 types of technology commonly used in brake controllers:

1. At the very low end are the "time delay" controllers. These use a very simple, very stupid, and very dangerous circuit that increases current to the trailer brakes proportional to how long you hold the brake pedal down, but do not respond to how hard you push it. In a panic braking situation, they provide almost no trailer braking during the first critical seconds; OTOH in traffic where you frequently are using long periods of light braking, they will ramp trailer braking up to the maximum after several seconds ... and that causes excessive trailer braking and a lot of jerking. IMHO this is a downright dangerous device that should be banned from the market. Aficiondos of time delay controllers often argue that their proclivity to provide too little braking on the highway and too much braking in the city can be dealt with by adjusting the delay (also called ramp time), and/or "gain" (also called ramp rate) ... and the makers of these devices make a big issue of how easily they can be adjusted while you're driving. To which I say that first of all, a truly good controller will self-adjust for conditions, and secondly the last thing I want to be mucking with in a panic braking situation is the gain on my trailer brake controller. Time delay controllers have one thing going for them - they are cheap. New owners often choose them on the basis of price alone, and so on that basis, they remain on the market.

2. The next level up are the pendulum based "inertia" controllers. These use some form of mass to measure deceleration of the tow vehicle and therefore provide current to the trailer that's proportional to how hard you are braking the tow vehicle. Hence, unlike the time delay controllers, they will provide maximum trailer braking in the critical first seconds of a panic stop ... and they won't cause excessive trailer braking during extended periods of light braking in traffic. These typically cost around $100 ... a good example is the Tekonsha Voyager. The weakness of pendulum type controllers is the moving mass is affected by gravity as well as by deceleration so they tend to provide too much braking on descents of mountain grades. Another problem with these is they must be mounted more or less horizontally so the moving mass is absolutely level. But they work well on flat land and are a far, far safer/better controller than the time delay types. I'm not sure that there are any "moving mass" controllers still made. The inertia controllers below have largely supplanted them. Of course they still show up on the Used market occasionally.

3. A significant step up from the pendulum based inertial controllers are those that use dual solid state accelerometers to measure both the effects of gravity and the effects of deceleration. Sometimes called "self leveling inertia controllers", these use advanced circuits to determine which direction is "down", regardless of how they're mounted and how steep the grade is ... so they always provide exactly the right amount of trailer braking. The prime example of this type of controller is the Tekonsha Prodigy which retails anywhere from about $110 to $150. This is the controller I have and find it works superbly for mountain towing. It never needs to be adjusted to accomodate different situations (just set and forget), never causes jerking of the trailer, can be mounted at almost any angle, and is not affected at all by steep mountain grades. It has no moving parts, so it should be extremely reliable.

4. Another controller that provides trailer braking that's highly proportional to tow vehicle braking is the Jordan Ultima. It uses a mechanical cable attached to the brake pedal to measure pedal movement ... and provides trailer braking proportional to how hard you push the brake pedal. It costs about the same as the Prodigy class controllers but is a little harder to install because the mechanical cable has to be attached and correctly adjusted. However, as of 2008 or so, it appears that Jordan has gone out of business, and I know of no other controllers in this category.

A new (and perhaps promising) brake controller technology is found in the unit from BrakeSmart. This one uses a pressure transducer that's tapped into one of the brake lines coming out of the master cylinder. Guaranteed to provide truly proportional braking since trailer braking is tied to actual tow vehicle brake fluid pressure ... but it's pretty costly (around $400) and requires tee-ing into a brake line.

Since the difference in price between the truly bad time-delay controllers and the very good controllers like the Prodigy or Jordan is less than $100 ... but the difference in safety and smoothness of trailer braking is immense, the intelligent choice is to spend a bit more to get a whole lot more.

I use my TM as a base camp for hiking, kayaking, mountain biking, and climbing Colorado's 14ers

The Trailer: 2002 TM Model 2720SL ( Mods: Solar Panels (170 Watts), Dual T-105 Batteries, Electric Tongue Jack, Side AC, Programmable Thermostat, Doran TP Monitor System)

The Tow Vehicle: 2003 Toyota Tundra V8 SR5 4X4 w/Tow Package (Towing & Performance Mods: JBA Headers, Gibson Muffler, 4.30 gears, Michelin LTX M/S Tires, Prodigy Brake Controller, Transmission Temperature Gauge)

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