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Hydraulic question

Sun Apr 29, 2012 7:55 pm

Looking for some opinion from some that have knowledge of hydraulics. My friend just bought a utility trailer from a guy the builds them. He does a pretty good job at it and just built his first dumper. A 5 x 8 foot, dump trailer, titled at 3000#, single axle.



Well, my friend tore off a roof and had 2000 pounds of shingles in it and went to dump them at the local dump. Went to activate the dump, has a pump, resivior, and battery on the tongue in a metal box. Well the bed only lifted slightly and that was all. Hydraulics would not lift the bed hardly at all. My friend called the guy and the guy said he would replace the 2" ram with a 3 1/2" ram.



Does this seem like what should be what will fix the problem. Asked my friend if the were any rating plate on the pump but he didnt know. Hope what this guy is saying will fix this problem as I guided my pal towards this trailer. Thanks for any info from anyone that knows more than I on this.

Re: Hydraulic question

Sun Apr 29, 2012 8:33 pm

I have a small dump trailer as well. Mine is 5x8 with dual axles rated at 4k lbs (if I remember correctly).

On mine, if well loaded, the ram and hydraulics will have a hard time dumping the load. You can see the ram flexing the bottom of the floor as it pushes the load up. Several times I've had to help with unloading the material before the ram would finish the job. I'd be afraid of increasing the size of the ram or increasing the pressure of the pump for fear of structural damage to the frame or body of the container with it overloaded.

It could be that the pump is too small, the ram is too small, the battery wasn't charged fully, the geometry is setup wrong, the load was too far forward, the load was more than 2k lbs, or a combination of any of the above.

Re: Hydraulic question

Sun Apr 29, 2012 8:33 pm

I didn't do the math but going from a 2 inch cylinder to a 3 1/2 inch cylinder will increase/improve the current lifiting ability of the cylinder by about 3 times.

Only problem is that the lift will be slower.

Re: Hydraulic question

Sun Apr 29, 2012 11:51 pm

Eugene wrote:Only problem is that the lift will be slower.


LOL, current cylinder WON't lift it. 3.5 x bigger should eventually lift it-making it much faster.

Re: Hydraulic question

Mon Apr 30, 2012 8:26 am

Dale Shaw wrote:
Eugene wrote:Only problem is that the lift will be slower.
LOL, current cylinder WON't lift it. 3.5 x bigger should eventually lift it-making it much faster.
Semantics, Dale. Your statement is true. I assume they will have to unload the trailer to change the hydraulic cylinder.

Re: Hydraulic question

Mon Apr 30, 2012 10:04 am

I agree with everybody on this page- and I did the math- the force will be increased 3.06 times, using the pi x r squared formula. But then there's all those other factors mentioned above.

Re: Hydraulic question

Mon Apr 30, 2012 10:22 am

Dan, Eugene and Bob are pretty close with their figures. If you had a 2" cylinder with a 1.5" piston and a 2000psi pump, the cylinder would have about 6,283 psi of push, the same cylinder with a 3.5 bore would increase to 19,242. The 2" cylinder would travel roughly 6.1 inches per second and the 3.5 would only travel about 2" per second. That's calculations from Surplus Center's online calculators. Also make sure what Raymond says about the structure is going to handle the increased power.

You stated the shingles only weighed 2000 lbs, if the guy ever loads the trailer with good topsoil, the average cubic yard(thats only 3'x3'x3') weighs average 1.5 tons(3000lbs with online calculator)) so it doesn't take much to put a sizable load on the trailer real fast.

Rick

Re: Hydraulic question

Mon Apr 30, 2012 8:54 pm

Thanks for the knowledge guys. Lucky for my friend, there was a bobcat at the landfill and was able to drag off the shingles. So now he is waiting on the larger cylinder. Not much of a downside that it will lift slower. Better slower than not at all. Thanks
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