Brain power needed physics

[ANNAMEL]

Ok guys this is what i have. You know i am building a BIG BOGGIN truck at work and now i am working on the hydraulic lift to get you up in it. I have figured out the lifting arm that stay level during a full movement from ground to bottom of door.Not the problem. The problem is i am limited to space with the cylinder. Instead of 2 pivots mounts for the cylinder i know there is a way to put 3 pivots (one mounted to frame) (center mounted to cylinder)(other end mounted to lifting arm) with the hydraulic cylinder at the center pivot to decrease my cylinder stroke. If anyone has any experience with this let me know. Thanks a ton. Hope this isnt tooooo far out there Mod.

 

[Donuts1]

What about using a rocker system like this but modifying the arm lengths to get the ratio you needed. Could run a very short stroke cylinder and have lots of movement on the other end....just a thought.

 

[ANNAMEL]

thats what i am looking for. i will look at your build thread and check the pics out. Is there any rule of thumb that might help our is this trial and error. Thanks for the help[cl

 

[ANNAMEL]

I will try and figure out how to put a drawing on here to scale for ya to look at. Thanks again

 

[moronthethrottle]

Another option might be a telescoping cylinder.

The only trick with what you're attempting is the actual geometry. Your lift will have some arc with the three point lifting mechanism-which for your purposes probably doesn't hurt anything. We sold the top-folding portable conveyors that worked under the same type system. Works fine, just takes a bigger bore cylinder to move the same amount of weight. I was going to put a pic of it on here, but it turned out to be really big, so here is a link...Hydra-Fold

 

[sneakysnake]

Without measurements or pics this was my brainstorm on the idea.LOL
Run the ram with the frame,use a pivot, have your step on a slide to move up and down.Sorta like a power window movement

 

[sneakysnake]

Another idea, might study the geometry on a backhoe. They use levers and pivots.

 

[Donuts1]

thats what i am looking for. i will look at your build thread and check the pics out. Is there any rule of thumb that might help our is this trial and error. Thanks for the help[cl

It's kinda a trial and error thing. Wish I could be more specific, but don't know how to explain it without typing a book...lol! PM me and I'll give ya my phone # if ya want and I can give ya my little bit of knowledge on it...lol!

 

[ANNAMEL]

I GOT IT!!! Man let me tell ya this contraption bout kicked my but. I used a shaft with a rotating collar like donuts front suspension. Kuddos to ya donuts! What i needed at the bottom i just put in the distance from my pivot point on the collar. Got the cylinders and pump hooked up today and lifted some guys to the top. Only thing is I am using one pump and running both cylinders so the lightest one goes up first and the heaviest one comes down first. I was curious if i went in the bottom of shaft #1 came out the top and went to bottom of shaft #2 and come out the top and go back to pump would that equalize both cylinders. Will post a video the end of the week for ya to check out. Thanks for your help.

 

[Sam_Fear]

Don't quite get how you are using 2 cylinder, but if they are different sizes, the bigger one is going to have less lift with the same amount of hydraulic pressure. I think you'd need to restrict the pressure going to the smaller cylinder. Trying to get that balanced would probably be tough though.

The other possibility is that I have no idea what I'm talking about.

 

[ANNAMEL]

I have a lift for both sides of truck. One cylinder for each lift. I ran 1 line and Teed off two each one. Just did some research and am putting a flow divider on it that will do 50/50 preasure to each cylinder. Both sides are equal in size and weight until someone steps on one and the other is not loaded. Its amazing how much you can learn when trying to figure something out.