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Brake sound
For some time now, our brakes make a horn sound when the air releases from releasing the brakes. We refer to it as our clown horn. A prevost tech said our brakes are fine and “some older coaches do that”. That may be true, but we don’t want it anymore. I did not see a way to upload a video with a video of the sound, but I did attach a picture of the part I believe creates the sound. What is this part and will replacing it fix the sound?
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10 Replies
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When you release your brakes the R-12 or R-14 valves are releasing the pressure that had applied the brakes. As that pressure is released it makes a noise. Normal.
The only alternative is to find out which relay valve is making the music, and then start swapping different brand valves to see which one make a noise you like.
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The noise is not just air releasing. It truly sounds like a horn and then pulsates on and off, from loud to softer until you can’t hear it anymore.
I don’t hear this from other buses? -
Perhaps you could upload a youtube video and post a link or title.
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I have that “clown” noise too. It comes from the treadle valve when releasing the brake. Air gets released through the exhaust port. There is a plastic shroud around the exhaust port to prevent dirt from entering. That is probably what we are hearing vibrating. I think it is normal.
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It looks like a Bendix Quick Release Valve. See p.28 of this 116 page pdf file: LINK
There’s a bunch of different valves, but there is just 1 maintenance kit, # 104463.Call Prevost Parts, they should have the correct one, or cleanup your old valve and find the original pt#.
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I changed my Quick release valve up front a couple of years ago (Bendix) and the R-12 for rear brakes and R-14 for E-brake and all Bendix and Pedal valve and it always sounds like a duck sound but it is quick it does not linger on. It started on HWY 20 a logging road and the front brakes weren’t releasing rite away the duck sound had a couple of second delay so I changed the front Quick release valve 1st and it did not fix the problem so I replaced thepedal valve and problem went away. I replaced the relay valves R-12 and R-14 just for maintenance reasons.
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I have ordered a new quick release valve. Where is the “pedal valve”? Do you have a part number? Thank you for the responses.
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The Pedal valve is in the steer compartment easy to get to the old valve was a Bendix # 109174 E-15 as per Prevost part changed to Bendix # 800632 E-10 had to use top part of old valve just a metal swing part that pushes piston down, mark all lines before removing take pictures. old on top new on bottom.
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I’m just posting the solution to my “clown horn” was as simple as putting on a new quick release valve.
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Thanks
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