Electric brake problem

Looks like mine do after around 30000km of dusty roads. Poor braking wise, I just replaced the magnets on my unit, the wires coming out the magnet assembly were starting to fray and though they still tested with continuity weren't apply any real braking.

Drum locking up, friend on a trip couple of years back replaced complete backing plates and drums before the trip, tested ok around home, on the road he found one was heating up. Backed of brake shoe tested ok. After a few goes of backing of the shoes replaced the bearing, again tested ok. Yep down the track heated up again, this time cut the wires to the magnet still didn't solve the issue, everything looked fined, could not work out why the brake would start dragging. Ended up having to take out the brake shoes for the trip. While all this was going on a brake mob also checked it out and couldn't see any problems. When he got home he replaced the backing plate, shoes and magnet again and that cured the problem.

Wear on the brake drum and magnet seems normal to me. I had one brake locking up and overheating after many k's, fitted a new magnet and the problem went away, but the old magnet looked fine.

Sometimes the manufacturer will route the brake wires to one brake and then across to the other one, this can cause problems with different voltages to each brake.

The face of the drum where the magnet runs looks normal to me and the brake magnets aren't worn out either, because the dimples are still quite deep.
Perhaps the brake performance is because the wiring to the magnets isn't allowing proper current flow or even the controller isn't set to drive it hard enough although you think it is doing the job.

A normal globe of around 30 watts connected to the brake pin and the earth wire pin should see the globe increase in brilliance as the manual control is progressively applied. That ensures the system is really able to work and meter out energy to the brake magnets as required. Just because people apply 12v to the brake magnet wire of the trailer doesn't necessarily mean the system is all working as a complete unit. The trailer end might check out ok but the front section could be the problem.
The van brakes should be able to easily do more then the van weight and make braking distance shorter than just the vehicle alone can do.

If the brake intermittenly locks up it is nearly always because the adjustment is TOO slack and the servo action of the brake design suddenly wraps the shoes ON and they hang on until the direction of rotation is reversed. Proper close adjustment should see the brakes work correctly. They are designed to do that, not suddenly get hammered wedge like, onto the drums with the shoes initially out of their best working position.
People are trained from birth to think a grabbing brake is adjusted too tight, not so. Too tightly adjusted is dragging the shoes.
Adjust brakes to firmly lock the drum from rotating and then reverse the adjustment wheel until free running is achieved. The shoes must be seated by "full locking", to position them prior to backing it off so they sit and work properly.
On a recent trip a mate with LC and 2 axle van had a wheel locking, I adjusted the brake to be closer, as above, and the problem disappeared.

I would get rid of the grease cap shown and fit a new one, instead of one which looks like it has been 9 rounds with Jeff Horn the boxer. Lose it and you have bearing problems quite soon.

Classic under adjustment of the shoes with the severity of the electric brake controller set to high .That's why you have to back up to release the shoe that is jammed on .
As the brake is applied the shoes are forced out too severely with the under adjustment of the shoes they jam at the leading edge of the shoe. (All of the surface of the shoe should make contact with the drum) backing off shoes makes it worse .

Fix - adjust shoes up so they are just skimming the drum .make sure the handbrake is adjusted right off first ( most people only adjust handbrakes by cable this is wrong ) it holds the shoes out in the incorrect position for correct adjustment. Back off the cable and make sure handbrake lever at the rear of the backing plate is right off and adjust shoes first ,then cable adjustment.
Adjustment of brake controller -There should be two different setting on the brake controller. .Back off the severity (How quickly and hard they come on ) of the brake controller (Set too high) and then increase the pressure setting if needed after test run .This allows the brake to be applied in a controlled manner with the full surface of the shoes making full contact.
Follow this procedure and you won't have any more problem with brakes jamming
I have fixed many van brakes .

HI
brake magnets look normal
When u cannot see dimples throw out
When uneven wear throw out

Drum magnet area looks like normal wear and tare
When badly grooved throw out
When worn flush with back of studs throw out

Always adjust brake linnings with some/little consistant drag . Do from rear with flat screw driver . NEVER EVER back off .

Backed off brake can lock up
Why by the time it actuator arm moves thru the its range of motion brakes do not apply till late in its travel . THIS WILL CAUSE sudden aggressive brake lock up .

ALWAYS when servicing linnings emery tape linnings and drum surfaces .
This will ensure smooth braking also.

Brake service is easy IF DONE PROPERLY

Always service bearings regular common sense

Nick

In addition to all that has been said about adjustment etc do not overlook an out of round brake drum.

One van that I had one wheel constantly locked every time the brakes were applied and stayed locked, just as per your issues. I eventually cut the wires to that wheel so that I could continue the trip and on my return home had all drums machined even though they all looked good and measured up OK, no more trouble.

Regards
Athol

Okay thanks everyone for your help here ....
have now adjusted brakes and they are a lot better , no lock up so far .
They don't appear to be at there best but may need to bed in ??
cheers everyone