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Topic: Spring brakes not releasing (Read 367 times) previous topic - next topic

Spring brakes not releasing

Hi everyone,

My current neighbor at MOT just went to dump and his brakes would not release although he has 125 PSI.

He had some work done on his step a couple days ago where they increased the pressure

99 U320
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Spring brakes not releasing

Reply #1
All of them? That's interesting. It's not seeing the pressure I would think.
Well I don't have a solution I would be wondering what the cause is? At least he's in the right place to get it fixed.
'99 U320 40 WTFE
Build #5462,
1500 Watts Solar 600 amp Victron lithium
2012 Jeep Grand Cherokee Overland Hemi
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Retired

Re: Spring brakes not releasing

Reply #2
Yes he is
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Spring brakes not releasing

Reply #3
There is a relay valve that the treadle valve activates that controls both rear maxi releases. If he can find it try tapping it.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Spring brakes not releasing

Reply #4
Could be a problem with the PP-1 valve.  That's the one connected to the push-pull knob on the dash.  They make repair kits:

Bendix PP-1 Repair Kit
1993 U280 SE 40' WTBI, Build: 4359
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960 watts on the roof (6 x 160)
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Re: Spring brakes not releasing

Reply #5
I'll let him know.
Thanks
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Spring brakes not releasing

Reply #6
Hi everyone,
My current neighbor at MOT just went to dump and his brakes would not release although he has 125 PSI.
He had some work done on his step a couple days ago where they increased the pressure
99 U320

My suspicious mind gets triggered when a new problem creeps up after "servicing."  In this case a system pressure increase that ordinarily shouldn't have been a problem, has now caused a valve failure in a life-critical system.  I'd start a new ticket and have, at least, the air portion of the braking system thoroughly inspected and parts replaced as necessary.

Most people see an air pressure gauge, a red light and an annoying buzzer.  I see a pneumatic logic system designed to provide controlled application, rapid release, dual braking circuits, air pressure preservation in case of a broken air line and  fail-safe brake application.  If you don't do a DOT air brake test every morning, well, best you go first.  I'll watch the show from the back.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
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AA1OH (H)e who must be obeyed.

Re: Spring brakes not releasing

Reply #7
I had that happen in Rocky Mountain NP in my Buffalo Bus. I set and released the brakes at least 20 times until it finally let go. Took a while as I had to build pressure quite a few times. This was a DD-3 can but could  happen to ours U300 also.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Spring brakes not releasing

Reply #8
Good morning everyone,
My neighbor started his coach this morning and cycle a parking brake on and off a couple of times and they released.

Thanks again for all the input
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH