I pulled onto the freeway towing our 25-foot sailboat. I looked in my mirror, and I was shocked to see heavy smoke coming from all four trailer wheels. I quickly pulled to the side of the road, and slowly drove to the next off-ramp. The brake components were very hot, and the wheel hubs were starting to get hot. I inspected all visible brake components, but could find nothing amiss.
The next day I tried towing again to see if the problem would repeat, and it did, with all four wheels smoking. Since the brakes were getting hot before the hubs, the source of the heat must have been the brakes, not the bearings. I inspected all the brake components again, but still did not find anything out of the ordinary. I was stumped.
This was going to require more sleuthing. My trailer is equipped with a surge brake system, with disc brakes at each of the wheels. Determining the cause of the problem was going to require a good understanding of the theory of surge brake operation and the design of the actual hardware installed on my trailer.
After doing some research, I found there is a wide variation in the design of boat trailers and brake systems. Boat manufacturers generally do not make trailers for the boat. Rather, boat manufacturers utilize the many independent trailer manufacturers located throughout the country. Also, there is little standardization of trailer design. Manufacturers usually produce trailers by bolting together components they select from the many component manufacturers, including axles, brakes, actuators, wheels, fenders, lights, bunk boards, and rollers.
Further complicating the picture, not all states have the same legal requirements for trailers. Therefore, retailers may sell a single model of boat with different models or brands of trailers depending on location. As a result, a single model of boat can be paired with a variety of trailer designs and components. Moreover, the amount of information available about a trailer and its components varies greatly by manufacturer.
Surge brake systems are the most common type of brakes used on the 7 million boat trailers in the US. In contrast to travel trailers that ordinarily use electric brakes, surge brakes activate mechanically, operating independently of the tow vehicle brakes. This eliminates problems that water causes with electric brake components when submerging the trailer during launching.
Surge brakes use hydraulic pressure to activate the brakes. The system consists of an actuator/coupler assembly, where the front of the coupler attaches to the ball on the tow vehicle. The back of the coupler has a sliding connection to the actuator, and the actuator is permanently attached to the trailer frame. The actuator contains a master cylinder, which connects to the individual trailer brakes via hydraulic brake lines. The individual brakes can be either drum or disc, similar to a car.
Warren, no offense taken; it was clear you don't drive the kind of roads I do. Those "Deadman's Curve" labels are not symbolic or imaginative, so my luck was actually quite good. The big problem I see is not enough warning symptoms before failure occurs, as well as brakes not designed to handle the amount of use required on long descents, no matter how much you use lower gears. We've got deer, too, up here and one took out the entire front end of my first husband's 1965 Mustang, which had a V-8 and a heck of a lot of steel in it. I bet you've got some great mud stories, though--and that's *not* sarcastic.
You're right about the roads in California. I'm from Chicago and my first time driving in California I was shocked by how tight the turns are on the exit ramps.
tekochip, that's a whole 'nother subject that many drivers have complained about here: tight curves on exit ramps, as well as very, very short exit ramps in some places. OTOH, when driving in New England, especially Massachusetts, many years ago, I was amazed at how poor the freeway exit signage was in letting people know what exits to take to get to specific places, (XYZ village name instead of Highway XX North, Highway XX South). It reminded me of some areas of Britain: you had to be a local to understand where you were going and which road took you there. The last time I drove there, in the early 2000s, I did see some improvement.
Warren, Ann and tekochip: Here's some more info about the driving conditions I was experiencing when the trailer brakes started smoking. That day I had only driven a short distance with the trailer, all on level roads. Before entering the freeway, I had driven less than two miles from home through town at a maxim speed of 35 mph. When I entered the freeway, the brakes started smoking within the first 500 yards. I was not using the brakes because I was just getting up to freeway speed.
Regarding riding the brakes, some interesting dynamics occur with surge brakes. In steep downhill situations, controlling the speed of the tow vehicle by using a low gear and not riding the brakes does not avoid the potential for the trailer brakes to overheat. Regardless of how the speed of the tow vehicle is controlled, if it creates a great enough resisting force against the trailer inertia, the surge actuator on the trailer will apply the trailer brakes.
One reason I was so surprised with the overheating was that just the week before this problem occurred I had towed the boat on a 500 mile trip. That trip included mountainous roads and 100 degree air temperatures. Although there were problems with individual brakes on the trailer, there was never any problem of all four wheels smoking. Interestingly, this trip included going down "The Grapevine" grade on Interstate 5, the main north-south highway in central California. This grade is about 6 miles long, has a 6% slope, and includes escape ramps for runaway trucks whose brakes fail. Despite the potential for the trailer brakes to overheat, the brakes appeared to handle it fine, with no smoking.
I still have a boat, but have not used it in years. I am about to buy a new truck and want trailer braking.....I never thought about what you mentioned ...thanks!
There is a basic flaw with the very concept of surge brakes, which is that there is no way to apply them without braking the tow vehicle. I am aware that they allegedly have a breakaway application device, but that is of no use when you simply need to apply brakes on the trailer, which you need to do non the occasion that the trailer is forced into an oscillation mode, either by the shockwave from a truck passing too close, or a number of other causes. And if your vehicle brakes fail, that surge brake is not available to slow you at all. So the first step is to replace the surgen brake with a system that can work. One "older concept" system uses the tow vehicle's power steering pressure and a control valve piloted by the tow vehicles brake system pressure to activate a hydraulic cylinder on the trailer that drives a secondary master cylinder. That system can have an electrical valve to provide remote operation of the trailer brakes, for emergency and parking use. Other systems have used tow vehicle engine vacuum to drive the trailers master cylinder. Of course, all of them cost more than a surge brake system, but all of them beat driving without any brakes.
I have stopped nmy van, while pulling a travel trailer, using the trailer brakes alone. It is not nearly as good as the four-wheel brakes were, but I did get stopped. That was when a front brake line bust on my 1985 Dodge van. Contrary to the claims, when you lose front brakes, you have no back brakes either. At least, not on a Dodge from that model year.
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