backyard "hydraulics design for amateurs" - tilt trailer cylinder

Hose fittings. Single hose fitting=single acting, two, double acting. You can put vents on many double acting cylinders to use as single acting.

Roughly. Use diameter and pressure rating to calculate force available. (hint-use the diameter to calculate the area acted upon by the pressure) Make sure to reduce the area by the size of the piston, if there is one on that side. Most guys check the column in the catalog that says "force available" or similar.

Mostly. If the seals are working.

Depends on the load and the design of the tailer. Best is a design choice. Bigger and longer means more fluid to pack around.

You can only get the trailer so empty, then you run out of work to do. The location of the cylinder, and the location of structure suitable for the cylinder to act on, determine the location more often than the stroke of a cylinder does, in my experience. The cylinder does not care if it is run to full stroke or not.

No. If it's built as a single acting cylinder, that's what it is.

You really need to get hold of some catalogs.

Farm implement places and "surplus" places usually deal in Hydraulics stuff. It is well covered in their catalogs. Do a little chinese blueprinting. Look at what has been done, There are reasons for everyone using a similar layout and parts. They work.

Cheers Trevor Jones

On Sat, 04 Aug 2007 09:35:48 -0400, dave wrote: I'm sure that you'll get more answerers to your questions then you expect but I'll lay a little groundwork:

A double action cylinder will have a hydraulic oil connection to both ends of the cylinder although as in CAT blade cylinders the connections will be at the same end but one will have a pipe going to the other end.

First there are balanced and unbalanced cylinders. The balanced cylinders have the piston rod extending all the way through the cylinder.

The formula for a single action cylinder would be Pi X radius squared of the piston(in inches) X PSI divided by whatever constant you want to get pounds /Tons/Etc.

For a double action cylinder the formula would be: Pi X radius squared of the piston O.D.(in inches) minus Pi X radius squared of the piston rod X hydraulic pressure in PSI divided by any constant you need to convert to pounds/tons/etc.

There are also double action cylinders that are not balanced so in that case you use the formula for a single action cylinder on the end without the shaft and half of the double action formula for the shaft end.

Usually you also figure in a fudge factor to make sure it really is big enough like adding 15 - 25% :-)

Up, Down, Sideways, don't make any difference.

Well, space does enter into things a bit. If you want to raise the front of the body 6 feet in the air and the cylinder is connected to the front of the dump bed and the trailer hitch it will have to be a one of those multiple sleeve cylinders like a fork lift uses - which probably costs a bit.

If you are serious about building a hydraulic dump trailer then go look at dump trucks and copy the design. They have been b building them for yonks and pretty well come up with the best ways to do things.

Whether the cylinder is partially full or partially full of oil makes no difference as the pressure is constant throughout a closed system.. Most designs are sized so at full travel there is some small clearance between the piston and the end cap.

Not really.

Bruce in Bangkok (brucepaigeATgmailDOTcom)

"dave" wrote: looking to buy a used hyd cylinder on ebay (or some similar source) for use in a home-brewed tilt trailer. have a couple amateur hydraulic questions: (clip) ^^^^^^^^^^^^^^^^^^ The answers you have received are all correct, but your questions indicate that you don't know enough about the basics to even consider such a project. Without understanding the engineering, you could look at other trailers all day and not absorb the important design criteria.

Things that could go wrong:

1.) You could start the project and never finish it. 2.) You could wind up with a trailer that doesn't work, or doesn't work very well. 3.) You could wind up with a trailer that breaks with the load raised, and kills someone. 4.) You could wind up paying someone to unscramble your mess, and spend more than the cost of a ready-made trailer.

Cross-sectional area of the piston in square inches times pressure in psi sq.inches times pounds divided by sq.inches = pounds lift

Not the ones that are actuated by a lever/piston mounted to one end of the cylinder, otherwise yes.

Go look at one and copy their design.

You could certainly spend $20 or so on an engineered set of plans ..

GWE

Or, he could start the project and learn. Giving up never taught anyone anything.

b

Dave, do I have your permission to post your response to me?

If it is a displacement cylinder, it does. They may have no internal stop and the shaft/piston will simply be pushed out of the cylinder. A very bad situation now covered with hydraulic oil!

--Andy Asberry--

------Texas-----

All the cylinders I have ever seen, aircraft or industrial, either limited out against something, whether that was the end of the cylinder or a limiting device, or were restrained by the item that they were moving, as in, it only has so much room to move.

It seems a dumb idea, to me, to build a mechanism that will come apart if not stopped before the end of it's travel.

Cheers Trevor Jones

"Trevor Jones" wrote: or were restrained by the item that they were

^^^^^^^^^^^^^^^^^^ That's the thing Andy A was referring to. If a cylinder was restrained by the thing it was bolted to, and was then removed and sold on e-bay, the buyer could accidentally drive it apart and spill oil all over.

Will someone tell me why a double-acting cylinder would even be considered for a tilt bed or a dump bed? Wouldn't gravity would be sufficient for lowering?

thanks for your help, guys: trevor, brucedpa, grant, andy. 'light intro's' to hydraulic cylinders requested, and received, and very much appreciated :-)

ps - I'm in Gainesville FL, in case of any of you guys sort of near have an ol' cylinder that might do me some good :-). I'm guessing something in the *roughly* 3 to 4 inch diameter range, 24 to 36 inch stroke 'more or less'. I'm a bit on the cash-poor side, but have 'oceans' of extra tools, components, and hardware type stuff to barter...

again, thanks :-)

toolie

Northern Tool+Equipment have dump trailer blueprints for A 10'X5' and A

14X6'4" in there master catalog. There asking $34.99 and $39.99 for them. They also have 2 books on trailer design in there.

Good luck on your project. H.R.

There is a lot of info in a granger catalog or some other catalogs that sell hydraulic parts. I think the new MSC catalog even has some info on Hydraulics. Northern Hydraulics has a page or two on designing hydraulic stuff.

John

A closed system, positive action (to deal with mud, damage, or decay), and the ability to have the trailer both move as required, and be locked in the desired position hydraulicly, are what comes to mind.

It would be a little more complex, and perhaps only a percieved benefit, but I could see it.

Cheers Trevor Jones

Even though it's more spendy, you should consider getting a pre-fab "tilt-bed hoist kit" (that usually comes with the trailer or truck-bed mounting and design plans) for your first project. There are way too many things to go wrong, some that can bite you *hard*.

They use one or two short large OD cylinders (6" to 8" range) in a "Scissors Jack" linkage arrangement underneath the bed, and all the engineering work has already been done - the jack assembly is much less likely to grenade on you due to unforeseen forces in the jack. There is a reason for the oversized bushings and pins...

Weld the jack in position, hook up the hydraulic lines to the 12V pump on the trailer tongue, connect a battery, purge the air out of the cylinder and lines and you are done.

Then you only have to make sure that the bed, hinge and chassis are built strong enough so they don't break during use, and the suspension is stiff enough so the entire trailer doesn't get up high in the dump mode and fall over sideways from trying to dump an unbalanced load - either of which could /really/ hurt if you are standing in the wrong place.

Oh, and you always dump a tilt trailer while hitched to the tow vehicle for the same reason - you don't want to chance the trailer 'turning turtle', going over-center and onto it's back.

-->--

"Trevor Jones" wrote: A closed system, positive action (to deal with mud, damage, or decay),

My automotive bottle jack, my automotive hydraulic scissor jack and my hydraulic press are all single acting. They do not present any problems from the fact that they take in air as the cylinder extends. As to locking the tilt bed in place, that is accomplished by closing a valve, trapping fluid in the cylinder. The extra complexity of a double-acting system to handle the possibility of sticking seems like huge overkill.

You could, of course, slip the end of the trailer under a load, and use it for lifting, or maybe for pulling stumps.

How about turning off the HTML?

None of those single acting cylinders will likely ever see a load in the "pulling" direction, such as when the load is moved past the pivot point of the trailer.

Cheers Trevor Jones

"Trevor Jones" WROTE: None of those single acting cylinders will likely ever see a load in the "pulling" direction, such as when the load is moved past the pivot point of the trailer. ^^^^^^^^^^^^^^^^^ If I understand you, you are picturing a load on the aft end of the trailer, trying to push the bed down, and "stretching" the cylinder. Good point I hadn't thought of. It could suck in fluid from the supply, past the check valves. But, couldn't you stop it by just closing the control/bypass valve between the pump and the cylinder?

Does the kit that Bruce Bergman recommends use a single or double acting cylinder?