Travel trailer brakes - magnet question
No photos, sorry. Brakes are similar to those in Sticky thread here. 3 major parts - 2 shoes and magnet on some "arm", for lack of better word. Being not a mechanic, I hope my descriptions make sense....
Forum Discussion
I'll add my thoughts.
I know you are thinking the magnet is the issue, however odds are high it is not the magnet.
The clip, yes the clip is in the middle of the magnet and the spring is behind the magnet pushing. However the clip really only comes into play when the drum is off so the spring does not push the magnet off the end of arm. See here
The brake before clean up. This is as it looks when the drum was just pulled off
Now cleaned up. As you can see the magnet is not flying off the pivot arm.
See here even better.
The spring creates light pressure to self feed the magnet up against the face of the drum. As wear comes, the magnet moves a little more. The magnet is kissing the inside of the drum all the time. Here you can see straight in. The magnet has room to move out on the arm as needed, just the clip comes into play when the drum is off. Think how fun it would be to put the drum on without the clip. The magnet would be falling off constantly.
There is one other thing about the magnet, it needs power to become a magnet. Unless you have power on the coil there is no magnet force attraction to the drum.
What you are describing points more to the brake shoes being forced to the drum by something other than the magnet. Did you take the adjuster apart to clean it? If so did you readjust the brakes after?
Is the pivot arm froze up? does it pivot? It may be froze, on.
If it is not those more common things, then be looking for something that is jamming the shoes outward.
As to how far and how fast, if the shoes are expanded to the point they stop spinning within an inch of moving, that is a lot of drag. Heat will build quick when moving at much any speed even 15 mph will create heat. Once the heat gets hot enough running a a level of speed, the lining can swell a little (thousands)and make the problem, even worse. At these temps you can start frying eggs on the drum.
Soon a brake fire, greases etc will set off if it runs like this long enough. And can affect the bearings and seals in time.
How long it takes to get to the real hot stage? That is a pure guess, but 1,000 feet with a brake locked on can create a lot of heat. Speed makes it accelerate rapidly. So how far do you have to limp? If this is miles, you need plan B. B = Short of a flat bed to haul the trailer, the drum has to come back off.
PS, By some odd reason, is the emergency break away switch pin pulled or partly pulled?
Hope this helps
John
almot wrote:
I opened this one brake because it wouldn't spin after the hurricane with mud up to the axle. It turned out to be just mud inside. Bearings were fine, I repacked the front bearing since I opened it anyway. Could've lost some retaining ring from that "arm" that magnet is sitting on - while opening the drum, or some time earlier. So the magnet is now pushed by the spring from behind all the way to the inside surface of the drum. This is I think what happened. Sand is like water, you drop something and it's gone.
Q2: what this washer or ring might be?
I know you are thinking the magnet is the issue, however odds are high it is not the magnet.
The clip, yes the clip is in the middle of the magnet and the spring is behind the magnet pushing. However the clip really only comes into play when the drum is off so the spring does not push the magnet off the end of arm. See here
The brake before clean up. This is as it looks when the drum was just pulled off
Now cleaned up. As you can see the magnet is not flying off the pivot arm.
See here even better.
The spring creates light pressure to self feed the magnet up against the face of the drum. As wear comes, the magnet moves a little more. The magnet is kissing the inside of the drum all the time. Here you can see straight in. The magnet has room to move out on the arm as needed, just the clip comes into play when the drum is off. Think how fun it would be to put the drum on without the clip. The magnet would be falling off constantly.
There is one other thing about the magnet, it needs power to become a magnet. Unless you have power on the coil there is no magnet force attraction to the drum.
What you are describing points more to the brake shoes being forced to the drum by something other than the magnet. Did you take the adjuster apart to clean it? If so did you readjust the brakes after?
Is the pivot arm froze up? does it pivot? It may be froze, on.
If it is not those more common things, then be looking for something that is jamming the shoes outward.
As to how far and how fast, if the shoes are expanded to the point they stop spinning within an inch of moving, that is a lot of drag. Heat will build quick when moving at much any speed even 15 mph will create heat. Once the heat gets hot enough running a a level of speed, the lining can swell a little (thousands)and make the problem, even worse. At these temps you can start frying eggs on the drum.
Soon a brake fire, greases etc will set off if it runs like this long enough. And can affect the bearings and seals in time.
How long it takes to get to the real hot stage? That is a pure guess, but 1,000 feet with a brake locked on can create a lot of heat. Speed makes it accelerate rapidly. So how far do you have to limp? If this is miles, you need plan B. B = Short of a flat bed to haul the trailer, the drum has to come back off.
PS, By some odd reason, is the emergency break away switch pin pulled or partly pulled?
Hope this helps
John
