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-   -   Air Brake Anti Compounding Valve (https://www.wanderlodgeownersgroup.com/forums/showthread.php?t=33896)

Snowpig32 05-14-2019 08:02 AM

Air Brake Anti Compounding Valve
 
Dose the BMC come equipped with a anti compounding valve to prevent spring / air overload?

I read once, one should not press the brake pedal if the parking brakes are on. This statement caused me confusion and concern. I had asked truck drivers about this and have yet to get an understandable response.

Having no previous knowledge of air brakes myself I did not know there was a spring break and service brake within the same air chamber. I have come to this conclusion on my own and it’s probably wrong, but if your parking brake is on and you apply service brake could this multiple x2 braking pressure cause damage to some air brake parts like chamber, chamber housing, adjuster, drums, etc..

I am seldom parked on a flat parking surface, mostly on an incline. I disengage the parking brake she is going to roll.

In a none air brake vehicle, I always have foot on the brake with pressure when moving the transmission from park into gear, seems silly to make this statement.

In an Air brake equipped vehicle with no Park only Neutral, should one anticipate the roll and keep their foot off the brake until after the parking brake is released? I cannot imagen everyone is doing this.
Please help get me back on track.

I have posting this in the BMC area because I believe it pertains to the Spartan chassis components more so than the Blue Bird.

Rick 05-14-2019 08:32 AM

Quote:

Originally Posted by Snowpig32 (Post 451894)
Dose the BMC come equipped with a anti compounding valve to prevent spring / air overload?

I read once, one should not press the brake pedal if the parking brakes are on. This statement caused me confusion and concern. I had asked truck drivers about this and have yet to get an understandable response.

Having no previous knowledge of air brakes myself I did not know there was a spring break and service brake within the same air chamber. I have come to this conclusion on my own and it’s probably wrong, but if your parking brake is on and you apply service brake could this multiple x2 braking pressure cause damage to some air brake parts like chamber, chamber housing, adjuster, drums, etc..

I am seldom parked on a flat parking surface, mostly on an incline. I disengage the parking brake she is going to roll.

In a none air brake vehicle, I always have foot on the brake with pressure when moving the transmission from park into gear, seems silly to make this statement.

In an Air brake equipped vehicle with no Park only Neutral, should one anticipate the roll and keep their foot off the brake until after the parking brake is released? I cannot imagen everyone is doing this.
Please help get me back on track.

I have posting this in the BMC area because I believe it pertains to the Spartan chassis components more so than the Blue Bird.

Just don't go over board with the foot pressure.

Randy Dupree 05-14-2019 08:34 AM

I have never heard you should not put pressure on the foot brake when the park brake is applied.
I don't think anybody that drives an air brake bus will release the park brake without having a foot on the brake pedal.
I could be wrong,ymmv

Alever 05-14-2019 08:52 AM

Breakdown of brake rear brake chamber cutaway picture.
 
1 Attachment(s)
Here is a good idea of how the service parking brake assembly works. The service brake works on one diaphram with air pressure when brakes are applied to stop. The parking brake will push against the back of the service brake diaphram when there is 60 psi or less air pressure in the parking brake allowing the spring to apply pressure to the back of the service brake. It takes 60 psi of air to release your parking brake. I have attached a cutaway picture. The picture showed a non servicable type of brake chamber that cannot be taken apart for safety as the spring is very dangerous. There is also a brake protection valve in the system to keep you from overloading the brake hardware when the parking brake is applied. It reduces the air pressure to compensate for the force of the spring.

Hope this helps.

LDM680 05-14-2019 09:23 AM

Jim:


Here is a video about the anti-compounding valve:


https://www.youtube.com/watch?v=LmrP_BxMfOI


Cheers


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