Are all of your trailer brakes working and how do you know?

[E_J_push_n_wind]

I posted this question in General RVing because I wanted this question to get as much exposure as possible, I think this forum gives it more exposure than it would get in towing or on the technical forum.

Anyhow,we all assume that all is well with our trailer brakes when we head out if we give the manual actuator a "throw" and we feel the trailer respond. After all, why would you think anything else?

Well, I just got back from a 3300 mile trip to WA state and back and if I wouldn't have had a Fluke Ti100 thermal imager with me. I would have been in the dark.

As it turns out, I borrowed one from work (wonderful they let us do that) to take with me on the trip for the purpose of "scanning" the wheels and what not just to keep everything in check. I found out two things on the trip amongst other things. 1) I had one brake dragging and eventually one brake failed, both on the same side. Now, the brake that was dragging I know was dragging because it was running hotter that the rest when I stopped for gas and got a temp reading on the wheel assembly. It was reading upwards of 196 degrees and the other three were reading at about 160 degrees. I crawled under the TT and backed off on the adjuster a few clicks. It got me to thinking, this is the same wheel I had a blowout on back in June. Could have been the wheel just got to hot and caused the tire to fail. The Jury is still out on that one because I have no way to confirm that but it stands to reason that it could have been the reason for the tire failure. Especially since I had two failures on the same wheel inside of 6 months.

Secondly, the brake on the same side on the front axle failed. Again I know this because after reading at each stop for gas and all of the brakes running about the same temp of about 160 + or - a few degrees, that one in particualr read 86 degrees upon stopping and reading it. With a thermal immager you can see what is going on. The perimeter of the drum would of course show the hotest (bright red) and you could see the rest of the of the wheel assembly and their various temperatures as well. The imager discriminates very well as well so there is no confusing what is going on.

As it turns out, after getting the TT out of the shop and talking with the service manager, I had a magnet failure. The wire came loose internally. I asked him if it looked like the magnet had failed from day one and there was no ware on the brakes or if it looked like they were working and at some point it failed. He said it looked like it was working and at some point failed.

So, I pose the question. How would you know if you had a magnet failure or some other brake failure (electric brakes) short of all four not engaging? When I would brake, everything felt normal. No pull to one side or the other. I had effectively 75% braking which aint bad, but it ain't great either!

[Bull_Rider]

Find a gravel road with a good, level surface and get up to about 20 MPH and max out your brake controller. When you come to a stop, get out and look for the pile of gravel in front of each tire. There should be equal skid marks apparent on the road.

I shoot my brakes with an infrared thermometer. I took off the decorative cones from each wheel so that I can shoot the hub temps too. My brake temps are usually around 100-120 depending on how many stops I made just before taking the temps.

An infrared thermometer is very valuable for finding brakes that are not working at all, or brakes that are dragging.

[jmtandem]

Compared to your temps mine do look high. The only thing perhaps is the accuracy of your heat tracer or pyrometer, it could be reading low maybe or not. How do you know its accuracy? Ours is checked anually against a blackbody which is calibrated anually to the National Bureau of Standards for accuracy and certified for accuracy. Our thermal imager is accurate to within 2 degrees on either side of what the Blackbody reads.

Yup, you are correct. There is a lot of chance for variations in temps even where the temps are taken on the hub or brake assembly. I try to take the temps on each wheel at the same place as I am far more concerned with hub and brake temp variations than overall values. I don't pretend to think that the $39 Harbor Frieght probe is as accurate as what you use but I also can't think it is 40 or 50 degrees inaccurate either. Coming down Pikes Peak temps are checked by staff and at 300 degrees you are pulled off the road for brakes to cool. So, even at 160 you are still way under what would be considered getting hot. Kind of makes the diesel guys with exhaust brakes smile as they rarely (if ever) need the service brakes going down.

[RCMAN46]

I have a P3 controller. Each morning I read the current when I operate the manual slide full on. With my gain setting of 7 my current should be about 7 amps but more important the same as it was the last time I did the test.

Most 4 wheel trailers will draw approximately 1amp per volt applied.

[E_J_push_n_wind]

jmtandem wrote:
This is a good thread. This is also why I use a infrared temp thermometer to check hubs and brakes. All mine have been within 10 degrees of each other. I am a little surprised of the temps you consider normal as after towing more than an hour my temps are more like 115-120 degrees and that is with minimal braking and properly adjusted brakes.

Compared to your temps mine do look high. The only thing perhaps is the accuracy of your heat tracer or pyrometer, it could be reading low maybe or not. How do you know its accuracy? Ours is checked anually against a blackbody which is calibrated anually to the National Bureau of Standards for accuracy and certified for accuracy. Our thermal imager is accurate to within 2 degrees on either side of what the Blackbody reads.

restlesswind wrote:
I don't know about other brake controllers,but mine give me an amperage readout.There should be right at 3 amps current draw per magnet,with 12-13 amps when braking when all 4 are working.

For a while mine were only showing 9 amps when braking.With a little trouble shooting using a clamp-on amp meter I was able to find which magnet was not doing its share of work.Though the braking seemed to be fine.
There was a bad wire conection.I redid the connection and all is now well.

If I'm not mistaken, wouldn't the current draw depend on how hard you are braking? Mine shows current draw as well but it is never constant, it varies with brake input. How could you know based on that how much each magnet is drawing? Little input, little draw and again, not constant and more input, more current draw. Am I missing something?

[RoyB]

Its not too hard for me to tell if I am having brake problems when I only have two working for me haha...

Having said that I too do scheduled maintenance on the brake system. When I first hookup and hit the road I can tell exactly what my brake status is at the first stop sign before leaving my house area with me applying manual brakes only using the thumb paddles to stop both truck and trailer.

Every 50 miles is usually a pull out at a rest area of some sort and a good walk around is always the first thing done to feel the trailer wheels for excessive heat and the such... Then I hit the rest room...

Even looking for abnormal brake dust is important.

Roy Ken

[12th_Man_Fan]

When I do my annual inspection I jack up each wheel and turn it to listen for any bearing issues and/or tire problems. Then I go to the front and pull the break away cable and go back and see if the tire is locked up. If it won't turn I consider it good.

I do this for each wheel. Every couple of years I pull the drums and check the condition of the shoes and adjust them.

Hope this helps.

Doug

[restlesswind]

I don't know about other brake controllers,but mine give me an amperage readout.There should be right at 3 amps current draw per magnet,with 12-13 amps when braking when all 4 are working.

For a while mine were only showing 9 amps when braking.With a little trouble shooting using a clamp-on amp meter I was able to find which magnet was not doing its share of work.Though the braking seemed to be fine.
There was a bad wire conection.I redid the connection and all is now well.

[westend]

Yeah, sometimes it's impossible to feel just one brake assembly not working while underway. Heat measurement is a great indicator and a guy can check for magnet function with a compass or other magnetic indicator. I think the best way around this is to make sure all your wiring is good and to do a yearly inspection of the assemblies. Since most trailer brakes aren't self adjusting, adjusting should go along with the inspection.
I guess I've had great luck with shoe/drum brakes, none of mine have mechanically failed. In the old days, the hydraulic side of things was the first to fail.

[jmtandem]

This is a good thread. This is also why I use a infrared temp thermometer to check hubs and brakes. All mine have been within 10 degrees of each other. I am a little surprised of the temps you consider normal as after towing more than an hour my temps are more like 115-120 degrees and that is with minimal braking and properly adjusted brakes.