Forum Discussion

sealevel_ram's avatar
sealevel_ram
Explorer
May 28, 2014

My Parking Brake Will Not Release

My Ultimate Freedom with a Cummins ISL 400 and Allison transmission will not let me release the parking brake. I push it in to release, and it just pops back out.

I have noticed that it has been doing this a few times lately but always eventually released. Not so now, at least not yet. Air pumps up fine, and yes, I am holding my foot on the brake.

Any advice would be much appreciated.
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  • sealevel_ram's avatar
    sealevel_ram
    Explorer
    Jun 01, 2014
    gbopp wrote:
    sdianel wrote:
    http://rainbowrv.com/rv-talk/air-parking-brake.html


    Clicky


    Any idea where this is located on a Spartan chassis? Is there just one, or are they at every wheel?

    Thanks.
  • Gasman_2's avatar
    Gasman_2
    Explorer
    May 29, 2014
    100 psi should release the brakes. Do you have 100 psi on the front and rear both ?
  • sealevel_ram's avatar
    sealevel_ram
    Explorer
    May 29, 2014
    rcmiller32 wrote:
    100 psi sounds a little low for your max air pressure. should be in the 120 to 130 range. can take 90-100 psi just to compress the parking brake spring. sounds like the governor is bad.

    I should have said it goes OVER 100 psi. I will look and see how much over and try to adjust if necessary.
    I did have a repair done on my air system a couple of months ago. Maybe they messed up the max pressure setting.
  • John_S_'s avatar
    John_S_
    Explorer II
    May 28, 2014
    I would try turning the governor up till you hit 120. If it will not go up then you will need a new one. Cheap part but make sure you find one that comes on at 90 psi instead of 70. I know in my FT we need more air for the suspension.
  • rcmiller32's avatar
    rcmiller32
    Explorer
    May 28, 2014
    100 psi sounds a little low for your max air pressure. should be in the 120 to 130 range. can take 90-100 psi just to compress the parking brake spring. sounds like the governor is bad.
  • sealevel_ram's avatar
    sealevel_ram
    Explorer
    May 28, 2014
    sdianel wrote:
    http://rainbowrv.com/rv-talk/air-parking-brake.html

    Thanks for the link. It explains how it works. Must be a leak somewhere and the spring is not compressed so the brake stays set.
    I would like to know if anyone else has replaced or worked on this.
  • sealevel_ram's avatar
    sealevel_ram
    Explorer
    May 28, 2014
    happy-2 wrote:
    Can you pump the brake peddle till the compressor comes on and see how high the pressure goes?

    Pressure goes up OK, to 100 psi.
  • happy-2's avatar
    happy-2
    Explorer
    May 28, 2014
    Can you pump the brake peddle till the compressor comes on and see how high the pressure goes?

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