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Dump Setups

Discussion in 'Truck & Equipment Repair' started by jb1390, May 21, 2010.

  1. jb1390

    jb1390 Senior Member
    Messages: 710

    I am building a dump frame underneath my flatbed on my truck. I will be using a straight push cylinder (scissor was more complicated than I wanted to fabricate myself, and have it not break). My cylinder will be mounted back by where the spare tire was (removed it), and it will push toward the front of the cab. By my calculations, with a 24" stroke 3.5" bore cylinder, it should dump somewhere around 5000 pounds up to a 60 degree angle.

    Most of the setups I have seen that use a straight push cylinder push away from the cab. This is a far inferior setup regarding the angle that can be achieved AND the load that can be lifted. Both of these are greater by utilizing a cylinder that pushes toward the cab. Does anyone know why most of the setups don't do it this way?

    The only drawback I can see is that, if the structure fails, it could push the bed into the back of the truck. But mine will not fail, and commercially built stuff is also designed in excess of the required strength, so I don't really see that as an issue.
  2. mcwlandscaping

    mcwlandscaping 2000 Club Member
    Messages: 2,557

    How is pushing AWAY from the pivot point better?
  3. jb1390

    jb1390 Senior Member
    Messages: 710

    Away from the pivot point will allow for the most travel. It also places the upward leg of the force from the angled piston further forward. The further forward the lift point is, the more it can lift.

    The upper system in the picture is my setup.
    The lower one is how most setups I have seen are connected.

    Mine can lift significantly more weight, with more travel using the same size cylinder. Almost double the weight, in fact, if the final angles are similar and use the same cylinder.

    I can explain the math behind it if interested, I am just curious why most setups don't take advantage of the superior mechanism offered in the top system in the picture.

    JBennett May. 26 17.0262.jpg
  4. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    Is that go in GM 2500

    I wouldn't do. Frame is too thin and small.

    If you look at 3500HD or F350 with dually they are twice thicker and wider.
  5. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    My friend have 95 F350 with dumpbed

    It have 1 cylinder with 2 pistons.

    His cylinder mount near cab and it about 20-25% slope which help easily to push dumpbed up.
  6. Mr.Markus

    Mr.Markus PlowSite Fanatic
    Messages: 5,782

    2 way cylinder or 1? With the weight sliding off the back, if the load gets hung could be dangerous with your set up.
  7. jb1390

    jb1390 Senior Member
    Messages: 710

    How would it be more dangerous with this design than with a cylinder pushing from the cab? It is a single acting cylinder, gravity down. The top part of the cylinder is used as a reservoir.

    The frame is the weak point, I would agree with that. However, this is a personal use setup, I am not working for a gravel yard or anything. The frame holds an equivalent 6000 pounds dump load-which is more than I could safely carry on that truck with SRW.

    A cylinder pushing from the cab CAN be designed to lift the same amount as mine. It will just be WAY slower if it is designed that way. My current setup can reach 45 degrees in half the time my friends setup did-his pushed from the cab. I haven't measured precisely, but my setup dumps around 60-70 degrees.
  8. Mr.Markus

    Mr.Markus PlowSite Fanatic
    Messages: 5,782

    I think you'll find that your setup comes down slower, with a hung load at the back past the cylinder, weight would hold it up instead of pushing it down.(On a dump this can be dangerous) Still interested in the physics though... let me know how it turns out.
  9. jb1390

    jb1390 Senior Member
    Messages: 710

    Dump works great-I tested it out last night. No issue with it dropping down on its own weight. It actually drops a lot faster than my old setup-which utilized the original bed and a 4" cylinder with 24" stroke. My current setup uses a 3.5" cylinder which helps some. I will post up some pictures of what I did-and I'll try to take a video too. I'm very happy with how it turned out. I'll do some drawings of the physics behind it too.
  10. the_experience

    the_experience Member
    Messages: 75

    I'd be interested in just seeing your measurements. The only flaw I see in the design is that all the vertical force is concentrated on the back portion of the frame. This also means that a few thousands of slop in the pivot pins at the cylinder amounts to the cab end of the box swinging a lot further off to one side, but that doesn't mean it won't work.
  11. adksnowo

    adksnowo Senior Member
    Messages: 370

    I would like to see some pictures & measurements as this sounds like an interesting set up. I'm building a hoist for a flatbed now. Have installed scissor lifts & many of them are junk. This may work better.
  12. jb1390

    jb1390 Senior Member
    Messages: 710

    I will take some pictures of the setup. It works really well-dumps in excess of 4000 pounds, and no issues yet. It is much steeper than any setups I have used, which really helps if you back up a hill and want to dump a sticky load of topsoil or mulch.
  13. jb1390

    jb1390 Senior Member
    Messages: 710

    Here are some of the long lost pictures...... i am also working through building a similar setup on my neighbors 2006 short bed. I will post pictures of that as I go along.




  14. jb1390

    jb1390 Senior Member
    Messages: 710

    I need to get a picture of the bed all the way up..... I think it goes to 60-70 degrees, but I need to double check. It will dump about 5000 pounds-it will do a full cord of green oak.

    One thing I learned with the first setup I did-if you want to do this with a stock bed, it is worth getting the power up power down unit, compared to gravity down. With the flatbed it drops ok, but with a light pickup bed, it wouldn't always come down on its own.