Need info on installing a dump valve

Discussion in 'Flatbed Trucking Forum' started by Southern Flyer, Dec 31, 2012.

  1. twolane

    twolane Medium Load Member

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    For what it's worth, I've installed "dumpvalves" on my own spread-axle trailers and found the electric solenoid valves to be expensive, and un-reliable.
    I started using a simple air operated dumpvalve instead. Put whichever type you want in the line that feeds the rear air bags. Even tho the leveling valve operates off of the rear axle, the dumpvalve will dump air on the rear bags only. For controal of my dumpvalve I run a 1/4" "signal" line from it to the front of the trailer where it has a female q/d like an airline for an impact wrench. Since I never slide my 5th wheel, the line that used to controal that, has a male q/d fitting. That way anytime I want to dump the air on the trailers rear axle,,,I just flip the air-switch for the 5th whl. thats already installed on the dash.

    Bottom line...put the dumpvalve in the supply line for the rear bags!

    Ya want a valve that is "normaly open" so the only time it works is when you flip whatever swich you use.
     
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  3. Preacher87

    Preacher87 Bobtail Member

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    Thems be some pretty fancy HCV's you're running.

    All the ones ive ever ran have been along the lines of this lil guy..

    [​IMG]
     
  4. Southern Flyer

    Southern Flyer Bobtail Member

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    My truck was originally a fleet truck and for some sick reason it came with a air unlock fifthwheel that I never use, it's got a 1/4 line going to the cylinder so really I could unhook that line and make sure it has air coming out (the other part of that set up is a pull knob) and just put a coiled line on it with a quick disconnect for the truck and the trailer? Would that quick dump valve I've heard talked about work for that I noticed it has two ports for supply to the bags and my set up has one line that splits to two.
     
  5. twolane

    twolane Medium Load Member

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    Let try to answer...the only time air would come out of that line going to the 5th. whl. cyl.,,,is when ya flip the air-switch on the dash. That's why that air-line, can be used to operate a dump-valve.

    That's exactly what I do! I use a coiled 1/4" air-tool line from HomeDepot for example to connect to the 5th. whl. line air-line, with a male fitting. On the trailer,,,the the "signal" line has a female q/d. This lets me plug/un-plug that line between the truck & trailer.

    Not sure which dump-valve yer asking about but no matter which one you use, air or electric operated,,,needs to go in the supply line that feeds the rear
    air-bags.

    Just find the 3/8" plastic line that feeds the rear bags. Cut that line and install the dump-valve to connect that line back together. Pay attention to the "in/sup" and the out markings on the valve. The 3rd. port will be "exh" for exhaust. The end of the 3/8" line you cut will go to the "in" port,,,& the other end of that line goes to the "out" port. The exh. port has nothing to it. The small port will be labled Signal or just sig. This is where the 1/4" line yer gonna run the length of the trailer will connect.

    Did this answer it?
     
  6. Old Man

    Old Man Road Train Member

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    Oklahoma City, OK
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    From 393.205
    (g) Air suspension exhaust controls. The air suspension exhaust controls must not have the capability to exhaust air from the suspension system of one axle of a two-axle air suspension trailer unless the controls are either located on the trailer, or the power unit and trailer combination are not capable of traveling at a speed greater than 10 miles per hour while the air is exhausted from the suspension system. This paragraph shall not be construed to prohibit'

    Just trying to make it harder.....
     
    daf105paccar Thanks this.
  7. Southern Flyer

    Southern Flyer Bobtail Member

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    Yes that got it, ill just get the quick dump valve that has a port on each side and put each bag into that and then the line from the t off of the HCV to the supply side and mount it cause the 3 port electric solenoid I've got I don't think will blow air off as quick as it should, it's designed for use on a air fan clutch. I use those tectran air and electric lines in the bundle so I think I could run that 1/4 line from the tractor thru that loom and mount my disconnect up at the glad hands. Has the DOT ever asked what that coiled line is for, I'm sure their curious little minds would ask. You have been a great help and ultimately saved me a lot of work and money cause the solenoid I have now cost about $85 and that quick dump is smaller and only about $30
     
  8. twolane

    twolane Medium Load Member

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    Tried to edit my post above but didn't work.

    Once ya cut that 3/8" line, the end that goes to the rear airbags gets plumbed to the "OUT" port. The end that is leaking air goes to the "IN" or sup. port.
    It's imporntant you choose a "normally open" valve because when it's not activated, it's like it's not even there. Once activated, it will close the supply line, and dump (exhaust) the air on the rear bags.
     
  9. SHC

    SHC Spoiled Rotten Brat O/O

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    Westville, IN
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    Ok, I believe this is what you need to do, and hopefully it makes more sense.

    And to be honest, i just wanted to draw cuz I'm bored

    [​IMG]
     
  10. Southern Flyer

    Southern Flyer Bobtail Member

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    Rockmart, Ga
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    Well I look at it like this Old Man, it doesn't state which method you have to use to make sure the vehicle doesn't travel over 10 while the bags are down so they can just cry about it. All the Dot and the FMCSA are good for is making the ones of us who try to do right have more problems when these container haulers and illegals can cruise up and down the road with no hassle at all. It's all about who looks like they can pay a fine and who don't. I'm in the process of dealing with one particular Alabama Trooper who has singled me out and wrote me two times for tires that werent out of service tbat i just had replaced because he gets a kickback from the tire shop at exit 205 in Heflin. Only setback to using the airline method is them seeing it hooked up, where the electric method hides it better.
     
  11. twolane

    twolane Medium Load Member

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    Arizona
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    Just so theres no confusion....SUPPLY! The single air-line going to the rear bags either goes into a "T" fitting,,,then splits off to each REAR bag, OR sometimes its just a 90deg "T" AT one bag, then going to the other bag. NO MATTER! Cut the SUPPLY line that only airs-up the rear bags. DO NOT put the dump-valve between the bags!

    No, a fan solenoid wont do!
     
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