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20,000gvw 8x18 dump trailer motor too small?

Discussion in 'Trucks and Trailers' started by Ramairfreak98ss, Apr 2, 2010.

  1. Ramairfreak98ss

    Ramairfreak98ss LawnSite Silver Member
    Messages: 2,210

    we have a 2007 7x14' , 14k dump trailer, its "small" in comparison to the other trailer we got last year. Its a 8wide by 18' long by 4ft tall and a 20,000lb rating.

    The pump/hydro resevior is the SAME on both trailers.

    Now the 14k trailer, has dual hydraulic cylinders that lift up, it takes roughly 30 seconds to go from full down to full tilt with 2 pistons.

    The 20k trailer has ONE monster RUGBY 10 ton scissor lift, it moves SLOW, i mean if i ever got it to full height empty, it would easily chew up close to 2 minutes or longer.

    Not only is it obscenely slow, probably because of gpm of the same motor, but the fluid empties completely from the 2gallon small tank when its only half up in the air... i added THREE quarts to it today and got it to go up another 1/4 of the way, but still not ALL the way up. When i put it back down, the tank overflowed after going down half way :/

    So i pumped OUT the same 3 quarts and it went all the way down, again filling the tank. So do they MAKE larger tanks like a 4 gallon and larger motors for these? Trailer already had upgraded to 2 batteries and getting a couple monster marine batteries would fit somewhere underneath the trailer for the future.

    Im not an electronic hydraulic pump expert, please give me your opinions of what to do... trailer also hardly tips half full of mulch.

    I think the rugby unit is their TB-16.. its a 6x19" bore cylinder shaft for an 18' trailer... actually mine looks just like the one pictured on their page 1 of their PDF brochure http://www.rugbymfg.com/rugby-pdf/Trailer Hoist.pdf only has the rugby logo on it
    Last edited: Apr 2, 2010
  2. Gravel Rat

    Gravel Rat LawnSite Fanatic
    Messages: 9,544

    For what you have it is time to upgrade to a gas motor with a small pump on it I know its not something you want to hear but it is the best solution for the problem you have.

    I have a 12volt hydraulic pump set up on my F-450 it is slow as molassis I had to put a 4 gallon tank on mine I have a 3 stage post hoist something like you see on a big dump truck.

    Williams Hydraulics makes a pump tank combination just what you need it comes with all the valves you would mount it on the tounge of the trailer. You could power it with a small gas motor and do you think I could find it on the net.
  3. zabmasonry

    zabmasonry LawnSite Senior Member
    from C. VT
    Messages: 315

    speed aside, this seems like a manufacturer issue to me. speed aside, they should have sized the tank to lift the trailer all the way. Two Gallons seems massively undersized, My calcs suggest it needs more like a 12 gallon tank ( could it be 2 cubic feet?. One thought I have is that the piston is air locked, and thus may be not working right, although that doesn't seem likely. If the tank is undersized, I would make a stink about it.

    CLARK LAWN LawnSite Silver Member
    Messages: 2,526

    what are the sizes of the rams on both trailers? they could have the same surface area between the two just the bigger one is slower as it more area to fill. if you just bought this last year and it never worked since day one why didnt you take it bake to the dealer?
  5. meador56

    meador56 LawnSite Member
    Messages: 90

    hoist cylinders on electric pump are single action and use the cylinder to store oil.

    CLARK LAWN LawnSite Silver Member
    Messages: 2,526

    uuhhhh noooo
  7. zabmasonry

    zabmasonry LawnSite Senior Member
    from C. VT
    Messages: 315

    the more i think about this, the more I think that you have an airlocked cylinder. I think that the side of the cylinder that is acting as a reservoir has quite a bit of air in it. I think that what I would do is disconnect that from the system (set it up to drain into a bucket), periodically filling the tank, raise it all the way, hopefully ending the tank just about empty. Then reconnect the reservoir side of the system and hopefully it should go all the way down and work correctly.
  8. GravelyNut

    GravelyNut LawnSite Bronze Member
    Messages: 1,594

    Or something is plumbed wrong. With a double ended cylinder that uses only one end, the shaft end should serve as extra storage for oil. As you say, it may be airbound and not pulling oil back in to it from the reservoir. The tap to the tank should be in the bottom of the tank and not at the top of it. When working correctly, the cylinder should pull almost the same amount of oil from one end to the other. The difference being the volume taken up by the shaft and the little bit of air that remains trapped in the cylinder. The oil has to flow freely from and to the shaft end of the cylinder.
  9. Ramairfreak98ss

    Ramairfreak98ss LawnSite Silver Member
    Messages: 2,210

    it was a used trailer... built in 2005 and purchased in 2006, it was in pretty darn good condition minus a couple small things and of course this pump issue.

    I timed it the other day, with a half load of mulch in my small 14k trailer " so not really stressing the motor bad", took about 42-45 seconds for a full tilt dump.

    So the big trailer tilts half way "maybe" in at least 2+ minutes.
  10. Ramairfreak98ss

    Ramairfreak98ss LawnSite Silver Member
    Messages: 2,210

    could be..

    I believe the 20k 8x18 is a 6" bore, 28" stroke and 2.5" wide piston... its damn big! its the rugby LR28a, i guess from looking at it visually.

    The 14k trailer has twin probably 2.5" bore, 1.5" piston, ~28" stroke... so nearly the same.

    I also feel that since seeing nearly an IDENTICAL trailer on ebay, most have the hoist welded to the frame somewhere around the "middle" of the 18' long trailer frame. Mine is welded in the back 25% part of the frame, in between the axles of the trailer.... I think this makes the 10 ton hoist have the struggle with enough force/pressure to lift 75% of the weight forward of the hoist :/

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