jbpruett Report post Posted January 21, 2017 The front air gauge went from 0 to 230 and back again rapidly for several minutes and several times during our last 250 miles. The low air buzzer would sound while the gauge was going up in down. Upon arrival home I parked the coach in the garage, set the parking brake and left it for 2 weeks. When I tried to move it the brake on the left rear wheel will not release. Any ideas of how to fix the problem? Share this post Link to post Share on other sites
wildebill308 Report post Posted January 21, 2017 Welcome to the forum. My first guess is a bad air line. Did the air pressure come up to normal range? How do you know the RR released? Bill Share this post Link to post Share on other sites
abyrd Report post Posted January 21, 2017 I would also check the air pod on the left rear brake to make sure that the diaphragm hasn't ruptures. Jim B Share this post Link to post Share on other sites
kaypsmith Report post Posted January 21, 2017 1 minute ago, abyrd said: I would also check the air pod on the left rear brake to make sure that the diaphragm hasn't ruptures. Jim B I was about to make the same suggestion but I type too slow. 0 to 230? 230 is extremely high, or is this a typo, if it is correct, your air governor needs immediate attention. Share this post Link to post Share on other sites
abyrd Report post Posted January 21, 2017 Sounds like the left rear brake didn't set during the last 280 miles of his trip, I'm thinking that the diaphragm partially failed on the left rear and dumped his air and with the travel it temporally sealed itself then dumped the air again. Not sure if this makes and scents. In any circumstances I would also want to check the brake shoes and drum. Jim Share this post Link to post Share on other sites
manholt Report post Posted January 21, 2017 jb. Welcome! Sounds like Jim and Kay nailed it. Normal air is 0 to 150! Brake will set if below 75 on mine, also the alarm for low air will get your attention! On another coach, I had a separation on the LR air bag and a crack in the air line going to my gauge in dash....it did the same as you described, but it didn't go to 0 while driving, it did fluctuate between 85 and about 105 as long as it was in gear. At idle it would drop below 75...so to keep going, at a signal, I would have to give some gas, in gear with my foot on brake! Thankfully I was 120 miles North of Red Bay, when it happened. Carl Share this post Link to post Share on other sites
wolfe10 Report post Posted January 21, 2017 You may have two unrelated problems. Suspect the rapid 0-230 PSI on the gauge was a gauge, not actual air pressure issue. Were this to happen while driving, when it dropped below about 30 PSI, the parking brake would have come on. And I am not aware of any engine-driven compressor on an RV capable of "rapid 0-230 PSI". Particularly if humid or wet when parked, it is not uncommon for the brake shoe to "rust itself" to the drum. In most cases this can be freed by putting the transmission in D and using a little throttle. Then N. Then R and a little throttle. Do not go from D with throttle to R with throttle without returning engine to idle and going through N. If this does not work, you may need to use a hammer to shock the shoes loose. Be SURE TO USE SAFETY STANDS AND BLOCK THE WHEELS SO ONCE FREED UP IT WILL NOT ROLL. Yes, you could have a more serious problem, but start with diagnosing the easy stuff. Share this post Link to post Share on other sites
bm02tj Report post Posted January 23, 2017 I thought 60 psi was the magic number for auto apply install your caging bolt on the one causing trouble then you know it is not park brake just shoes sticking Share this post Link to post Share on other sites
manholt Report post Posted January 23, 2017 Apparently not, mine is 65, I guess it depends on what size coach you got! Carl Share this post Link to post Share on other sites
wolfe10 Report post Posted January 23, 2017 Are you referring to when the air pressure warning light/alarm comes on or when the spring brake actually applies??? This from the Texas CDL manual page 73. Section 5.1.14: 5.1.14 – Spring Brakes All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. They must be held on by mechanical force (because air pressure can eventually leak away). Spring brakes are usually used to meet these needs. When driving, powerful springs are held back by air pressure. If the air pressure is removed, the springs put on the brakes. A parking brake control in the cab allows the driver to let the air out of the spring brakes. This lets the springs put the brakes on. A leak in the air brake system, which causes all the air to be lost, will also cause the springs to put on the brakes. Tractor and straight truck spring brakes will come fully on when air pressure drops to a range of 20 to 45 psi (typically 20 to 30 psi). Do not wait for the brakes to come on automatically. When the low air pressure warning light and buzzer first come on, bring the vehicle to a safe stop right away, while you can still control the brakes. The braking power of spring brakes depends on the brakes being in adjustment. If the brakes are not adjusted properly, neither the regular brakes nor the emergency/parking brakes will work right. Share this post Link to post Share on other sites
manholt Report post Posted January 23, 2017 Brett. Me, light and high pitched buzzer. Never had spring brake come on while moving and don't ever want to!!! Carl Share this post Link to post Share on other sites
wildebill308 Report post Posted January 23, 2017 Yes I know how they work I have first hand experience. I blew the air line from compressor. The OP hasn't been back to answer any of the questions so far. Till then we could rebuild the whole system and not have it right. Bill Share this post Link to post Share on other sites
manholt Report post Posted January 23, 2017 Bill. It's only been 3 days and now it's Monday. He may be a worker bee or in a garage with no internet connection! Just hope he comes back with info on the cause, if he's in a garage! Share this post Link to post Share on other sites
