My dump bed drops down when it is about a foot and a half from all the way down. Dalton hydraulic cylinder and pump, 2200 lb trailer weight (guess,) tandem axles at 3500 lbs each, 5'x12' box. The guy I got it from thinks it may be air in the line but he ordered a one-way flow control valve which he says could fix it. How do I fix this? Also, he is making a pair of ramps so I can tow a small skid steer in it. He recommends that they be five feet long to make to be easy to manage and that they will work if I tilt the bed up (lowering the back end,) and then drop the bed down when I get to the top. Is this crazy? Thanks.
dump bed drops down
- Thread starter 1claydude
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AKKAMAAN
Veteran Member
Is the dumping design your own? (cylinder and "scissor leverage" etc) or/and can you refer to a online/upload picture of the dump design, and plumbing?
Air?? hmmm....
Design related?? Maybe, especially if dumping (up) starts with cylinder horisontal, and ends with cylinder vertical....
Hi, not my design. It starts out about 4" (should have measured) below horizontal at the lower mounting point and gets up to a 50 or 60 degree angle. I bought the trailer on craigs list from a guy who said he built it and had a manufactuers and dealers licence which he just decided not to renew earlier that week. I believe it was designed for a sissor lift and he changed his mind, but not the design, to keep the price down. Here are some photos. Let me know if you need more.
AKKAMAAN
Veteran Member
ooops...can't see any pic's yet...
EDIT:I do think you problem is from the design....My idea is this...
If cylinder starts around horizontal, it has a disadvantaged leverage position to the bed. I can see that it takes very high pressure to make bed start raising. The more the cylinder extends the better leverage, and lower pressure. When lowering the bed, at the position when it has "about a foot and a half from all the way down", the cylinder is almost fully retracted.
Would be great to see a video clip, showing the cylinder motion during a full dump cycle, up and down.
Leejohn
Elite Member
AKKAMAAN hit the nail right on the head....
AKKAMAAN
Veteran Member
Thanks LeeJohn!:thumbsup:
This is a very poor design, and it is basically impossible to use a cylinder like this, with out a linkage system to make leverage equal over the entire dump cycle. So it is not a hydraulic problem. It is a mechanical design problem. This current design do need extreme pressure to initiate the dump cycle, and over the time bed raises, leverage gets better and takes the stress of the cylinder and the rest of the design.
If you look at the horisontal position of the cylinder, it will rather push the bed backwards than lift it....:laughing:
The main limiting issue is that we need a cylinder that have a long stroke, but are very short retracted (to fit under the bed, and still allow ground clearance)
The are ways to make this work with out linkage, but then we have to use either 2 or more cylinders, or better using a multiple segment, telescopic cylinder, with a trunnion mount. (95% of all dump trucks overseas, use trunnion mount telescopic cylinders, centered under the bed. That also allows dump side ways too. Notice how the cylinder is in a almost square angle to the bed during the entire dump cycle )
A telescopic cylinder have some unique features for a design of a bed dump. It utilize the largest "piston diameter" at the start of the cycle, and the more the bed raises, the weigh on the cylinder decreases, and the smaller diameter segments can keep extending, at a faster speed.
Is it fixable? Do you have a picture of one done correctly? How far out of horizontal does it have to be? What about a shorter ram of similar strength and drop down the lower end (being careful not to bottom out?)