A Brake Diaphram

[Joe Camper]

Only half way there.

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When u first start backing the brake off by depressing the lock ring on the 9/16 adjuster nut the slack does not move. The shaft turns only.

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When the cams, not visible, bottom out on the brake shoe rollers, not visible, u will feel that for sure. Then keep going and the slack adjuster will move outward.

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The slack pulls the pushrod that squeezes the smaller service brake spring and when u install the new diaphragm there is no struggle.



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Another thing. Only between the clamps is there 2 seporate pressurized chambers. The emergency half that is energized only when u release the parking brake and the service side that is only energized when u r using the brakes for stopping. Outside the 2 diaphragms and clamps is open to atmosphere. If your unfamiliar with chambers and u want to verify what line is service and what is emergency the ports r not lined up and clearly visible what line is going to what half the chamber. In the photo the left line is feeding the serice brake side and the right one is emergency air.

[Joe Camper]

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Now I've removed the service brake clamp and with a tap the 2 pieces seporate and the diaphragm comes out.

In the photo I've turned the slack adjuster back to release the service brake sprint so u can see it.

Nother good tip. If u don't hold the spring down by backing the slack out first u r faced with trying to push it back during diaphragm instalation and it's much more difficult. When u push on this plunger u r not just compressing IT'S spring u r also having to overcome the springs that hold the brake shoes to the rollers. It's doable but unnessessary, do it my way.

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Now here is the emergency half opened up, again these r the old style very dangerous I'm showing this because I thought u might want to see and I know what I'm doing.

If u zoom in the middle u can see how the cage tool locks in from the back side.

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Here is the emergency half open with the diaphragm no longer present and I backed the cage bolt out as far as I could so that main spring is exposed.

[Joe Camper]

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Before u loosen these clamps note where the nuts r so u know how tight is tight. I take only 1 turn from 1 nut and the other completely off and it comes free. This makes reassembly better.

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So y put the diaphragm up and rest the clamps like in the photo before lifting the chamber back up.

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Then put the chamber up with 1 hand and bring the clamp into place with your other hand. Mild blows with a hammer while squeezing the open end of the clamp brings the 2 half's close enough togeather to get the nut and bolt started.

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2 last tips first before u go for the slack adjuster and release its return spring and adjust the brake, it's a good time to grease the s cam shaft. U got it almost 180 from where it normally sits when the slack is backed out. I'm pointing to that grease fitting for the S cam shaft.

Now go back to the adjuster on the slack and let the slack walk back, when it stops moving continue on the adjuster until u then begin to push the shoes outward and tighten down till the adjuster nut stops. If tight u cant turn the brake drum at that point u r bottomwd out the brake is tight . Then about a 1/4 turn back from tight is where I put the 9/16 bolt for the slack. pull the slack to check it. Make slight adjustments to feel if nessessary.

The less slack the better, however if u want them all equal and if 1 hub requires additional slack to release the drum sufficiently the rest need to be loosened to match its slack.

And that's it. How to cage a brake replace a diaphragm and a look at a old style chamber and it's main spring exposed.

Where else do u get this stuff?

[Gil_J]

Joe knows his stuff.

[Garynmike]

Holy Moly! I was just doing some research and I am really happy I checked out this thread! I had no idea of the danger and certainly won’t attempt this on my own.... so, I guess this really does make my phone call to Joe Camper all the more valid!