Chinese Brakes (maybe Lead not Asbestos)

[HowieE]

I had posted a question last month http://www.airforums.com/forums/f439...ion-39132.html , while on the road, about lose of brakes. While everthing seamed to check out as far as the controller and electrical items I had no braking. I removed 2 drums and found everyhting mechanicaly correct. What I did find was an excessive amount of dust. Dust to the point that the magnets were not floating on the arm but rather stuck in place. While that in it's self would not prevent the magnets from applying it cause me to question things. The shoe contact points and pivit points were all dry of lub and added some resistance to movement. Even with these short comings once the primary shoe made contact it should have moved the secondary shoe and resulted in braking. The only thing I could see that come up with was the amount of dust and that the dust was acting as a friction reducer and reducing contact pressure on the drums.

What I did do to get some braking while going home was to cover the baker plates with a plastic bag, all but the very bottom, and vacuum them through the adjuster hoke. While this did not provide Good Braking it did improve things a bit. Before vacuuming, and with the trailer jacked up, the brakes wouod not stop a turning wheel assembly. Afterwards the wheel would turn to a stop, not the real slam stop that one would expect from a suspended wheel.

When I got home I contacted Henschen and asked what if anything had changed in thier supply chain and if any similiar problems had been noted. After a very curt conversation they admitted that they are now using brake assemblies from China and "Good Luck" was the final comment.

I have not had a chance to open thing up yet, beacuse of the snow, but would be interested if anyone has had similar questions.

[Fyrzowt]

Interesting problem.
I'm curious about the comment in your title about lead. Do you have reason to believe they are using lead - and if so are you aware of any negative results?
Dave

[overlander63]

Tetraethyl lead was used as a valve seat lubricant and octane enhancer for many years. Not all lead will cause a friction reduction, but it does not hold up well in high heat applications, it melts.
I heard a rumor that China was recalling a massive amount of lead that had been exported. It seems it was contaminated with toys...

[klattu]

We used to chew lead for something to do,
And...I forget

[HowieE]

Originally Posted by Fyrzowt

Interesting problem.
I'm curious about the comment in your title about lead. Do you have reason to believe they are using lead - and if so are you aware of any negative results?
Dave

My comment as to Lead or Asbestos was just a statement as to the poor level of quality the Chinese have in the products they export. If they are putting lead paint on children's toys, insect poison in dog food and stuffing rags in as the filter medium in oil filters how should I look at thier brakes?

I am interested in finding the reason my brakes don't work. If it is confirmed to be the source then I will look for another. If in looking for the answer I advise others as to a questionable situation all the better.

Having worked with asbestoe most of my life and having had an asbestos management license while working I would much prefer to see asbestos back in brake linings. The length of any fiber expelled in brake dust is far to short to cause a problem. But that is an other discussion now in the hands of lawyers rather than governed by science.

[Excella CM]

It sounds like a defective lining formula. But you know the Chinese–they're just doing as best as they can.

[ROBERTSUNRUS]

Hi, sometimes we over look the obvious or the basics. Not knowing what, or how, you checked your system I would start with the seven pin connector first. At the Ford dealer, I just retired from, we had a Tekonsha brake control tester; Actually we had two different ones. The small one, as I called it, was only a tester with six lights that would test for power at all the right places, but the one, I called the big tester, was a large box with a long cable that plugged into your seven pin connector and the control panel would reach into the cab. On this tester it had switches, gauges, and actual brake magnets inside the control box. [you do the test while driveing your tow vehicle and makeing normal to almost panic stops] With this tester, it will show you actual volts and amps coming out of your tow vehicle's seven pin connector. Now that you know whether or not you have sufficient power coming from your tow vehicle, then I would work my way back to the trailer system. Most of the checks I've done were always the trailer's fault, but don't assume anything.

[dwightdi]

All brakes abrade to some extent and produce dust. Poor quality brake linings or pads wear faster than properly compounded harder material. Asbestos containing compound brakes were good as long as you did not inhale the dust. Excessive dust is twice as bad on our electric brakes as hydrallicly operated brakes as the coefficient of friction of the magnet (which contains brake compound) is reduced if there is dust present and therefore the activiating force on the operating shoes is reduced resulting in poor braking. Clean your brakes frequently of loose dust and replace the lining with harder properly compounded material when you can get around to it. You might also inquire from the three sources of brake magnets what grade of compound they are using in their magnets and buy the best available.

[HowieE]

Hi Robertsunrus

I have checked the electrical system back as far as the inside of the trailer. While I am only getting 9.5 volts at that point and 21 amps, 6 wheels, that in itself would not cause a complete lose of brakes. Yes I will up grade the thin wire Ford installed as I have had to do with GM products to reduce the voltage loss.

Hi dwightdi

You and I are thinking along the same lines. I had assumed the excess dust was reducing the friction on the shoes but reduced friction on the magnet would have the same or greater result. The 2 wheels I did remove while on the road I did clean with 1/2 can of brake cleaner each. This did improve things to about 1/2 of what I would have expected on each of those wheels. One thing I did notice that I was not happy with was excessive ware on one of the magnets and also the armiture faces. If it was in fact cheap magnets, of poor material, you mention 3 sources. Do you have names or a means of identifing those not comeing from the far east.

Of all the things we can no longer trust I had hoped brakes would have lasted a bit longer. I am at least thankful this happened in Fl. and not out west in the hills.