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Dump Trailer Cylinder Mount Design

Discussion in 'Truck & Equipment Repair' started by jb1390, May 9, 2013.

  1. jb1390

    jb1390 Senior Member
    Messages: 710

    Trailer A: Uses a cylinder that pushes backward (toward the hinge)

    Trailer B: Uses a cylinder that pushes forward (away from the hinge, toward the truck)

    Most designs use Design A. Design B will have a higher lift angle, and greater dump capability when using an identical cylinder compared to Design A.

    Why do most trailer designs use Design A?

    These are for straight push cylinders.....no scissors, which is a different animal altogether.

    The only thing I can think of is that there will be higher stress in the trailer frame, due to the mount point of the cylinder being closer to the hinge. But that seems like it should be easily solved.....and the function of the trailer is better with Design B.

    Trailer Design A.jpg

    Trailer Design B.jpg
  2. alldayrj

    alldayrj PlowSite.com Addict
    Messages: 1,108

    The distance from the pivot to the "lever" is greater with a therefore more force/leverage can be applied. Try opening a door from the hinge side vs the handle side
  3. jb1390

    jb1390 Senior Member
    Messages: 710

    I should add:
    My buddy bought a 16' dump trailer, and it only dumps to about 30-35 degrees, which is hardly adequate.

    His design is Design A. I think if we change it to design B, and reinforce the back section of the frame with plate, we can get it to 50-60 degrees with the same dump capacity. I remember when I did the calculations for the dump I built for my previous truck and my neighbors truck, the difference between design A and B was almost unbelievable in functionality....
  4. jb1390

    jb1390 Senior Member
    Messages: 710

    Yes I know this.....which is why design B should be all accounts be vastly superior. So why do most manufacturers use design A?

    Do a google image search of "dump trailer", it is amazing how hard it is to find a picture of design B.

    Edit: I see what you were thinking...and you were thinking that because the distance from the mount point of the cylinder on the trailer frame is further from the pivot point, the greater force applied upward to dump. This is not correct. What will affect it, is the distance from the hinge to the point at which the cylinder mounts to the dump body. The distance from the hinge to the cylinder mount on the dumping section of the trailer is one variable, and the 2nd variable is the angle of the cylinder, affecting the vertical leg of the force vector. If these 2 variables are identical, the direction the cylinder is pointing is irrelevant, it will start to lift the same load. You could even have the cylinder mount directly underneath or even behind the hinge and it will still lift (although that would be stupid because of the stress in the frame it would cause)
    Last edited: May 9, 2013
  5. jb1390

    jb1390 Senior Member
    Messages: 710

    Answer with Analysis

    So here (I believe) is the answer.

    Higher stress in the frame rails with design B.

    If you can get it done with design A (45 degree lift), why mess around with it?

    Both these designs in my models have the lift cylinder attached in the same spot. Which means the same dump capacity at initial lift.

    Design B will lift substantially higher, but if you can get 45 degrees as a manufacturer, you probably wouldn't care. It would be good enough for most people.

    For my friends trailer, I think we will be able to flip the cylinders to achieve a 45 or 50 degree dump, and reinforce the frame in the high stress area.

    Design A.jpg

    Design B.jpg
  6. dieselboy01

    dieselboy01 Senior Member
    Messages: 795

    My dump trailer uses "A" and I was wondering why also. With a heavier load in it you can see the back of the trailer (where it's hinged) lift up before it starts to dump. It dumps at a good angle, I've never hand a problem dumping anything but when it's all the way up the back of the trailer is about 2" from the ground, If the ground is a little uneven it will hit the ground. I was looking at the ram set up and was thinking of flipping the rams to "B" but this is the way it was engineered.

    I would call it a 45 degree angle.