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November 2010 Willie's Workbench

Odyssey Brake Control
Willie Worthy | Writer
Posted November 1, 2010

Trailer towing: more to know before you tow

In the August 2010 issue, I covered trailer towing and hitches. I promised Part Two the following month, but it just didn't get done then. Here it is now.

Trailer Brakes: The state laws requiring trailer brakes vary widely. My feeling is that if the total load exceeds 1,500 pounds, trailer brakes are required. Most states require brakes on trailers with a total load of 3000 pounds and over. The general assumption is that most tow vehicles can safely stop up to this much additional weight. From my experiences, most trailers are under-braked. Pulling a loaded car trailer without brakes just doesn't make good sense. Sometimes, one will see a tandem-axle trailer with only brakes on one of the axles as a money-saving measure. To me, it just seems that if it takes two axles to handle the weight, it's going to take brakes on both of these axles to handle the braking needs.

Briefly, there are two types of braking systems: Electric and hydraulic surge. Electric brakes require an in-vehicle controller that's activated by the brake pedal, hydraulic pressure, or a moving pendulum that senses motion. Hydraulic surge brakes have their actuator mounted on the coupler. As the tow vehicle begins stopping, the pushing trailer activates a hydraulic plunger that sends pressure to the brakes. Both types have their advantages and disadvantages. Electric brakes offer more versatile control but require the tow vehicle to be equipped with a controller. Surge brakes allow any tow vehicle to make use of the trailer's brakes, but don't provide the range of control that electric brakes do.

Load Balance: The way the load on a trailer is carried is very important. It should be evenly distributed with the bias being toward the tongue. Without the necessary tongue weight, the trailer can, and will want to, pivot on its axis (the axles) and will whip from side to side. Depending on total trailer weight, tongue weight should vary from seven to 15 percent; 10 percent is about average. Small utility trailers have no problem with seven percent. For example, a 1,000-pound loaded trailer should have about 70 pounds of tongue weight. Remember, this is a minimum figure. As the weight and length of the trailer increase, so should the percentage of tongue weight. When tongue weight exceeds the capacity of the towing vehicle's hitch weight, special equalizing hitches that transfer weight to both the trailer's axles and the tow vehicle's front axle are necessary. When the required tongue weights can't be met, so called "sway controllers," which use friction from either a sliding bar or a stabilizer shock to resist sway, can be employed. Actually, these really do help just about any trailer, regardless of the tongue weight, to handle better.

Determining Proper Tongue Weight: There are several ways to do this. The first thing you need to know is the overall weight of the trailer when loaded. This can be calculated if you know the weight of your trailer and the weight of the load. You're better off locating a scale. The local dump is a good source for a scale, and they will usually give you a weight for free. Commercial scales at truck stops are another source.

Getting the tongue weight is a bit more difficult. While at the scale, you could unhook your trailer, leaving only the tongue on the scale, which is not particularly feasible. There are special tongue-weight scales that will give you a very accurate reading but are pretty expensive for one-shot use. Actually, coming up with the proper tongue weight is pretty easy by making use of your bathroom scale. If you know that tongue weight exceeds the scale's capacity, then use an offset lever arm. Take a quality piece of 2x4 or 2x6 and lay it across the scale on one end, and place the other end on a block of wood the same height. Position the scale and the block of wood so that they are exactly three feet apart. Now place the tongue of the trailer, at its hitch height, so that it's not centered but two feet from the scale and one foot from the block. To be even more accurate, place a piece of pipe or tubing between the scale and the board and the block and the board. Now multiply the weight shown on the scale by three to get the tongue weight.

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