How do I test that these brakes work?

[jdege]

I have a trailer built with mobile home axles. Neither the lights nor the brakes work, and I need to replace the tires.

The question is do I simply need to replace the wiring, or do I need to replace the brakes, as well?

I know the wiring is bad - it looks like someone ran over the seven-pin connector, and I'd want to replace the lights with LEDs in any case.

But I'd like to know, before I start, whether I simply need to rewire the brakes, or whether they need to be replaced, as well.

Given that one, the brakes don't work, now, and I'm planning on replacing the wiring, regardless, I'm thinking that I'd simply cut the wire, and connect 12v DC to the two ends.

Should this work? I'm expecting that the magnet would move. Am I wrong?

 

[Lou Schneider]

The magnet grabs against the rotating brake drum which provides the force to pull on the brake linkage, so it may not move on a static test. You can see if it's producing magnetism by passing a compass in front of the wheel, it's needle will deflect violently if the magnet is working. Don't leave 12 volts connected to the magnet for too long, they're not made for continuous use and will overheat after a minute or two. The brake controller provides less than 12 volts except in a panic stop.

Best test is to jack up the wheel, spin it by hand and see if the brake shoes grab when it's spinning.

 

[John From Detroit]

I was going to make a suggestion but Lou Beat me to it.
Some brake controllers however will not engage brakes unless you are moving
In that case set brake gain high.. On a Gravel road have someone watch from a different vehicle as you brake.. ON A GRAVEL ROAD or other surface where the wheels can more easily slide. not on asphalt or concrete

But my guess is the wiring is the issue.

 

[RVfixer]

Wow, I could hardly believe what I was looking at in your photo. You need a lot more than wiring!! A different trailer would be best. It appears from your photo that the brake backing plate has a big broken-out area where you can look in and see the magnet, the brake shoe actuator arm and the vertical face of the brake hub...all highly rusted. I would give up on that one! I guess you could do a complete brake job including new back-plates all built up with shoes, actuator arms and magnets. Then you would need new wring and a brake controller. I could only guess what the wheel bearings look like but without looking I would say replace them...if the bearing races and stub axles are not completely rusted. My guess from what I can see is that you need new axles.



Unless you are doing a one time test you can't just cut the wires and apply 12 volts. For functional use the voltage has to go through a brake controller and be set up properly. The controller determines the amount of voltage to send back to the brakes using things like speed and brake pressure applied in the tow vehicle. You also need a battery "on" the trailer and an emergency break-away switch and cable. If the trailer becomes unhitched from the tow vehicle the cable pulls out a pin that allows the switch to close and apply full battery voltage to the brake magnets to keep the trailer from being a runaway.



The way these electric brakes work is braking voltage is applied to the so-called magnets. The current flowing through the magnet wire coils actually turns them into magnets. The magnets pull against the vertical face of the rotating drum. Friction between the magnet and the drum face moves the actuator arm and expands the brake shoes out to the drum horizontal braking surface. More brake pressure in the tow vehicle sends more voltage to the magnets which apply more pressure against the drum resulting in more braking.



The compass test, which I see posted often, is pretty much useless in my opinion. Yes, it will tell you that the some voltage got through the wiring and the "magnets" became actual magnets. It will not tell you if the brakes will actually work. You don't know if the shoes will actually expanded out to the hubs (that won't happen until the wheels turn with voltage applied to the magnets), you don't know if the magnets returned when the voltage was removed, etc., etc. The only way to tell if the brakes are actually working, without road testing, is to lift each wheel off the ground, apply brake voltage and turn the wheel by hand. The wheel has to turn a number of degrees for the magnet to move the actuator arm and expand the brake shoes out to the drums. That is a good test but it doesn't tell you if the brakes are adjusted properly, if the shoes are worn out or cracked and damaging the hub braking surface, if the magnet is returning and is not stuck out and wearing at an angle, if you have any broken springs, if the bearing seal is leaking grease on the brake shoes and more. You can only tell those things by pulling the wheel and the brake hub.



I have some time on my hands this morning so I'm going to keep writing...but you don't have to keep reading. I see a lot of people post that to set a brake controller drive on a gravel road and see if the wheels slide. That is NOT how you set up a controller. I guess you could check to see if the brakes are working at all that way. Setting a brake controller properly is important. If you set it improperly you can have the truck stopping the trailer or the trailer stopping the truck. Either way you will prematurely wear out some brake shoes and not be able to stop as quickly as you should in the event of a required quick stop. Set properly the tow vehicle and trailer brakes work together to stop the rig as one unit. Here is the best way to set up a controller: "Use the instructions in the manual for your brand controller." I have used two different brand controllers. Both manuals instructed to drive 25 MPH on a dry paved road. Both manuals said to not do this on a wet, gravel or dirt road. It gave a starting number for the controller setting and instructed to apply the brakes at the controller by sliding the bar, or squeezing the ears together or turning the know, depending on the controller, and apply full brake voltage...which would be the starting voltage that you set. Continue to increase the gain number until the wheels skid when you apply full braking at the controller. When the wheels skid, both manuals said to back off the gain until the wheels just do not skid on dry pavement and that would be the proper setting. Some controllers have lead and lag settings and the manual will explain how to set those up. In the case where the wheels don't skid at all, even on the highest setting the manual indicated where to leave the controller setting.



I should say that the "John from Detroit" post on using a gravel road is a reasonable reply to the Op's specific post of how to know if the brakes are working. However, I have seen this method on the gravel road slides posted here many times as the way to set up brake controllers...it's not!



OK, I'm done..............

 

[Gary RV_Wizard]

You don't need to use the brake controller in the tow vehicle to test. If the trailer has its own battery in place, you can pull the emergency "breakaway" switch to lock the trailer brakes. Or you can hook an external battery to the brake_ and Ground terminals on the trailer plug and activate them that way. See Lou's advice about voltage and time.

That inner side of that trailer wheel looks suspicious, so I'd consider installing all new brake assemblies, maybe on all wheels. They aren't terribly expensive.

https://www.etrailer.com/Accessories-and-Parts/etrailer/AKEBRK-35R.html?feed=npn

 

[SmokerBill]

I thought that mobile home axles weren't really built for regular use, but designed with only enough durability to be able to tow the mobile home from the manufacturer to its final destination at a mobile home park.

 

[jdege]

It's a 20-year old trailer, custom-built to carry a 37-foot sailboat I recently bought. I had someone inspect the trailer, before I bought it, and he said the wiring was shot, the lights needed replacing, but the brakes were good. That the surface rust was nothing to be concerned about.

Me, I'm not so sure.

The trailer is built using mobile home axles. The wheels are a bit unusual in that they have separate rims and hubs. Not really a problem, I have a source for the wheels+rims, if I decide to go that way.

I'm looking at three options:

1. Replacing the tires and rims.
2. Replacing the tires, rims, and brakes.
3. Replacing the axles.

Replacing the axles means moving the trailer to the shop that would do the work - which means getting the boat off the trailer. Not impossible, but a bit of a hassle.

Replacing the tires and rims is simple enough.

Replacing the brakes, though, I'm not sure. I've watched YouTube videos that make it seem simple enough, but how standardized are these brakes? I can see brakes like these available online, how can I be sure they'll fit? Is removing them always as easy as just removing a few bolts?

What I'm afraid of is deciding to replace the brakes, tearing things apart, then finding that I don't have the parts or tools to put things back together.

So, my wanting to see if the brakes work, if I cut into the wires and power them directly. If they do, I'll put on new tires, replace the wiring and lights, and make the 60-mile trip to the marina to put the boat into the water, and defer any additional maintenance on the trailer until I have the boat off of it.

If they don't, I need to either replace the brakes as well as the tires, or have it towed into the shop to have more standard axles installed.

And that depends upon how likely it is that I can find drop-in replacements for the brakes.

 

[Old_Crow]

Trailer brakes operate with electro magnets. The magnets are attached to a lever that operates the brakes similarly to the way the parking brake on a car works. I don't think putting power to the magnets without the wheel/drum assembly rotating will do anything to tell you if they work or not.

Don't forget to pack the wheel bearings, while you're in there.

 

[Jkoht]

I'm sure you've heard what having a boat means? BREAK OUT ANOTHER THOUSAND. Get the boat off and bring that thing to a shop to have it done professionally, it'll be done right and you'll be happier in the long run.

 

[jdege]

I thought that mobile home axles weren't really built for regular use, but designed with only enough durability to be able to tow the mobile home from the manufacturer to its final destination at a mobile home park.

It's not the axles that are only rated for one-time use, it's the tires. An 8-14.5MH tire is rated for one-time use, but if you replace them with something like an 8-14.5LT you'll be fine.

And if my recent research is correct, it's common for the brake assemblies to be welded, rather than bolted in place, when makes replacing them more of a hassle. In my case, the brake assemblies are fine, mechanically. I just need to confirm that the electromagnets work.

Which are easy to access, one you pull the wheel and hub.

My confusion was from trying to learn how to do this with YouTube videos about trailer axles. Mobile home axles are sufficiently different to confuse things.