Intermittent brake lockup

[Gene]

Originally Posted by gnored

Brake backer plate? Never heard of it.

Gary Nored

When you remove the brake drum, there's a round plate mounted on the axle with things like brake shoes, springs and such. That, I believe, is the backer plate. I could be wrong, but that's what I recall it to be called.

Gene

[HowieE]

This is a shot of the backer plate of the brake assembly. The 2 springs at the top are the return springs. If the forward spring, as you look at the trailer with the brake drum removed, is weak, broken, or the wrong one the brakes will be able to lock up on their own. This is because as the forward shoe comes in contact with the brake drum, turning forward as you drive, it forces the rear brake shoe against the anchor pin, at the top where the 2 springs are hooked on, and with nothing, the spring to overcome this action, the brakes will lock.

Deitz645 beat me to it with the picture of the breakaway switch. Every trailer ever made with electrical brakes had one. If yours is not there someone as bastardized the trailer. I am sup prized that you have had the trailer to shops and they have not picked up on this problem.

[Gene]

Howie,

I haven't worked on drum brakes for a long, long time. How often do you replace the springs?

Gene

[HowieE]

You real should HAVE to replace the springs. The reason I mentioned them is if they were to fail a possible reaction could be brake lock up as I discribed above.

You clearly do not have a common problem so we may have to look for the uncommon that would result in your problem.

[Gene]

Howie,

I don't have any problems, Gary does.

I just wanted to know what you recommend regarding spring replacement. As my memory returns, I think it used to be recommended to replace the springs when the shoes are replaced, but shoes are made so much better now, they may outlast springs.

It appears the electric brakes are not self adjusting. Does that have something to do with being electric, or is it an example of ancient technology living on in Jackson Center?

Gene

[dmac]

Ancient technology... drum brakes & no self adjust.

[ROBERTSUNRUS]

Originally Posted by CrawfordGene

Howie,

I don't have any problems, Gary does.

I just wanted to know what you recommend regarding spring replacement. As my memory returns, I think it used to be recommended to replace the springs when the shoes are replaced, but shoes are made so much better now, they may outlast springs.

It appears the electric brakes are not self adjusting. Does that have something to do with being electric, or is it an example of ancient technology living on in Jackson Center?

Gene

Hi, Gene. As for replaceing the brake springs, it would be the same as with a car with drum brakes.

(1.) Replace the springs when the brake system was at one or more times extremely overheated. [or shoes worn down to the metal] This weakens the springs.

(2.) Replace the springs when they become rusty. Rusty springs get weak and will break. Not real common in this area of the country, but very common in other areas.

(3.) Springs break; From flexing and not being of top quality. Millions of springs are made and a few are going to fail.

(4.) When your trailer brake shoes and magnets are worn out, sometimes it is cheaper the replace them with complete backing plate assemblies instead of piece by piece. [springs included]

An old test we did ages ago was to drop the brake springs on the cement. the good ones would have a little Twang to them and the bad ones would thud, like a piece of lead.

[gnored]

Thanks for all the suggestions. I'm going to beg a rapairman south of here to take a fresh look at these issues, so maybe something good will come of it.

Regards,
Gary