need a bendix brake valve

David Anderson · February 04, 2021, 11:00:08 AM

Driving 70mph down I10 the other day and the parking brakes engage. Makes for an oh no moment. Fortunately I was in the geezer lane and was able to pull to the shoulder quickly because those brakes slowed the bus really fast.

The parking brake knob was still pressed in, and my air gauges showed 100psi on front and rear. I reset and got the brakes released and drove on home. Now, it takes 4 or 5 tries to get the brake released.

Where can I find this valve? Apparently the Bendix PP1 valve number 287515 is replaced by something else. The local parts guy offered a Haldex valve, but it was all plastic. I passed on that.
From the tag it looks like the valve should release the park brake above 60 psi. I guess that is what that pressure means.

I know the parking brake engages at some point of diminished pressure, but I believe that is part of the eagle plumbing that allows that to happen.

I confess I am not well schooled in the operation of the brake system safety features other than it has always worked flawlessly until 2 days ago.

Any suggestions?

Thanks David

richard5933 · February 04, 2021, 11:05:33 AM

Quote from: David Anderson on February 04, 2021, 11:00:08 AM
Driving 70mph down I10 the other day and the parking brakes engage. Makes for an oh no moment. Fortunately I was in the geezer lane and was able to pull to the shoulder quickly. The parking brake knob was still pressed in, and my air gauges showed 100psi on front and rear. I reset and got the brakes released and drove on home. Now, it takes 4 or 5 tries to get the brake released.

Where can I find this valve? Apparently the Bendix PP1 valve number 287515 is replaced by something else. The local parts guy offered a Haldex valve, but it was all plastic. I passed on that.
From the tag it looks like the valve should release the park brake above 60 psi. I guess that is what that pressure means.
Any suggestions?

Thanks David

Call Luke at US Coach in NJ at 856-794-3104. He's going to have the current replacement for this valve and should still be able to get it out in today's mail. He's typically in until about 4pm EST Mon-Thu.

buswarrior · February 04, 2021, 11:47:03 AM

While you are at it, you'd betterdo some testing of the low air warning devic in all the places your coach has them.

What year? Is this brake system stock, or been converted?

Sudden application of the parking brake, without driver intervention, and the control knb was still in position?

Very suspicious, i would be, that this bus was trying to kill me...

Prove it out to be fit.

Happy coaching!
Buswarrior

6805eagleguy · February 04, 2021, 12:35:04 PM

Almost the same happened to me, except the knob actually popped out. Very lucky, my brakes weren't adjusted, and the s60 literally didn't know the brakes were on

I just got a new valve from the local truck shop, but then again I have replumbed some things after someone hacked spring brakes on, which eliminated the need for 100 psi foot application to release

richard5933 · February 04, 2021, 12:46:26 PM

Quote from: buswarrior on February 04, 2021, 11:47:03 AM
While you are at it, you'd betterdo some testing of the low air warning devic in all the places your coach has them...
Buswarrior

Like he said - have you done a brake leak test with a pump down recently? Great time to remind everyone, especially new bus owners, that brakes should be checked at the beginning of every travel day for proper function, including the low-air warning light and buzzer and that the e-brake automatically applies when the pressure drops.

David Anderson · February 04, 2021, 01:16:01 PM

Quote from: richard5933 on February 04, 2021, 12:46:26 PM
Like he said - have you done a brake leak test with a pump down recently? Great time to remind everyone, especially new bus owners, that brakes should be checked at the beginning of every travel day for proper function, including the low-air warning light and buzzer and that the e-brake automatically applies when the pressure drops.

I did a leak test with a pump down when I got home. Worked fine. Low air warning worked. Light worked. E-brake automatically applied on dropped pressure. Everything worked as it should.
Air system had never been hacked since I bought this bus when Houston Metro retired the fleet. It's all stock, but like all of us, things are getting old.

richard5933 · February 04, 2021, 01:22:47 PM

Quote from: David Anderson on February 04, 2021, 01:16:01 PM
I did a leak test with a pump down when I got home. Worked fine. Low air warning worked. Light worked. E-brake automatically applied on dropped pressure. Everything worked as it should.
Air system had never been hacked since I bought this bus when Houston Metro retired the fleet. It's all stock, but like all of us, things are getting old.

Good job running through all those steps. Does sound like the valve might be in need of replacement. Luke would be my first phone call if I needed one.

luvrbus · February 04, 2021, 07:28:10 PM

David check the rear chambers for a leak the Eagles aired the chambers up like a 1 time charge of air.I doubt it is your PV that is bad .the chambers do rust and you probably need new chambers but they are cheap and easy to find at any truck supply

richard5933 · February 05, 2021, 03:05:14 AM

Quote from: luvrbus on February 04, 2021, 07:28:10 PM
David check the rear chambers for a leak the Eagles aired the chambers up like a 1 time charge of air.I doubt it is your PV that is bad .the chambers do rust and you probably need new chambers but they are cheap and easy to find at any truck supply

How would leaking rear chambers cause the parking brakes to apply if there is still 100 psi in the system? Or make them difficult to release? Not sure how the mechanism works to produce those results.

luvrbus · February 05, 2021, 03:26:50 AM

Spring brakes takes air pressure to release where DD-3 brakes exhausts the air to release the chamber on spring brakes the chamber is charged one time any small leak they will set unless it has been plumbed for constant air supply which Eagle and others didn't always do ,David has owned his bus for a long I am surprised he still has the original brake chambers in working order.His metro Eagle should have spring brakes but could have DD-3's if he has DD-3 it is a easy change over to spring brakes on a Eagle

richard5933 · February 05, 2021, 03:31:57 AM

Quote from: luvrbus on February 05, 2021, 03:26:50 AM
Spring brakes takes air pressure to release where DD-3 brakes exhausts the air to release the chamber on spring brakes the chamber is charged one time any small leak they will set unless it has been plumbed for constant air supply which Eagle and others didn't always do ,David has owned his bus for a long I am surprised he still has the original brake chambers in working order.His metro Eagle should have spring brakes but could have DD-3's if he has DD-3 it is a easy change over to spring brakes on a Eagle

I get that, but where in the system is the decision made to apply the spring brakes in an emergency? At the cans or at the parking braking valve? Unless that decision point is at the cans how would leaking cans cause the parking valve to self-apply?

luvrbus · February 05, 2021, 03:40:38 AM

Quote from: richard5933 on February 05, 2021, 03:31:57 AM
I get that, but where in the system is the decision made to apply the spring brakes in an emergency? At the cans or at the parking braking valve? Unless that decision point is at the cans how would leaking cans cause the parking valve to self-apply?

He didn't say the PV self applied ,he reset the parking brakes filling the chambers again and rode into the sunset.he is probably going to need new chambers and they are not exspensive around 100 bucks each for MGM spring brakes

richard5933 · February 05, 2021, 04:17:23 AM

Quote from: luvrbus on February 05, 2021, 03:40:38 AM

He didn't say the PV self applied ,he reset the parking brakes filling the chambers again and rode into the sunset.he is probably going to need new chambers and they are not exspensive around 100 bucks each for MGM spring brakes

Sounded like what he said to me, "Driving 70mph down I10 the other day and the parking brakes engage. Makes for an oh no moment."

The brakes self-applied. The question I'm asking is can that happen without involving the parking valve? If spring brakes can self-apply if the can develops a leak, wouldn't that mean that it's also necessary to check out all the plumbing to confirm that there isn't a leak somewhere else in the system as well?

luvrbus · February 05, 2021, 04:47:58 AM

Spring brakes have a built in 1 way flapper to prevent back flow

David Anderson · February 05, 2021, 07:26:14 AM

Quote from: richard5933 on February 05, 2021, 04:17:23 AM
Sounded like what he said to me, "Driving 70mph down I10 the other day and the parking brakes engage. Makes for an oh no moment."

The brakes self-applied. The question I'm asking is can that happen without involving the parking valve? If spring brakes can self-apply if the can develops a leak, wouldn't that mean that it's also necessary to check out all the plumbing to confirm that there isn't a leak somewhere else in the system as well?

Yes, you are reading me correctly. Driving 70 the parking brakes applied, but the knob was still in the release (off) position. It was not popped out. What puzzled me thereafter is how many times it took to release the parking brake after I drove 2 more hours and was in my driveway trying to put the coach in the barn. That made me think it was the pp1 valve, but now with what Clifford said, I don't know

David