Designing a Double-Acting Hydraulic Cylinder

you can find the cylinder size and information on most of the cylinder supplier catalogue. that will give you an idea on what size to used, no need to re-invent the wheel here.

But if you trying to get a design start you may first calculate the end-support -> the bearing size and pin size that can take your force of 30Ton. Then you need to calculate the piston thickness, the piston should hold the seal and at the end of the piston threre should be a lock nut able to hold 30Ton. All of that should give you an idea on the cylinder close length. next you assume a cylinder closed length with some additional parts like barrel cover thikness and front nut size, say 1400mm stroke + 500mm (bearing, piston thickness etc lenght) = 1900mm of cylinder close length.

then you check the cylinder rod diameter for bulkling using the cylinder open length (1900 + 1400). With your cylinder support specified and your compressive load is 30Ton, safety factor for bulkling = 2, you should be able to use the Euler formula to get the answer. round the answer up to 5mm or 10mm (or 1/2") for a standard rod size.

Once you get the cylinder rod size out, you find the area needed on the cylinder to get a retraction force of 30Ton when the pressure is 350Bar, you need to consider a efficientcy loss factor (I would normally use 95%). The area you get will be the anulus area of the cylinder ( the area of bore size minus the area of rod size), From there you can find the Bore size of the cylinder. Again you need to round the bore size up to 5mm or 10mm for a standard bore size.

Next you need to calculate the thickness of the bore using pressure vessel formula. A safety factor of 4 is normally use for safety purposes. You may refer to ASME VIII for a more detail calculation. With the bore thinkness and diameter know you can choose a tube / pipe size that is available on the market to used as the barrel.

I am not doing cylinder design myself but I would normally size the bore, stroke and rod and give to my supplier to get the cylinder design out completely. I would miss a few point but I think the main design procedure would be all there.

Thanks a lot Zichau.

I design my cilinders using data from this links "http://www.parker.com/ar/catalogs/polypak.pdf" and "http://www.parker.com/ar/catalogs/wiper_seried.pdf"

Greetings and salutations,

Designing a hydraulic cylinder is no easy task:

First things first:

What is the intended use?, what is the desired stroke length of the rod?, is the cylinder in question going to be base mounted with a pin and eye configuration on th end of the barrel?, Is the cylinder going to be trunnion mounted with pins in the side of the barrel with a two piece mounting flange on each side?, do you wish to use a double acting telescoping cylinder for this job?, You will need stop tubes in any cylinder type to reduce stress loading on the cylinder rods and stuffing box for the cylinder as it will want to sway even with multiple cylinders are used in any case-be it double acting single rod, double acting telescoping, differential telescoping etc.

Now to the really important stuff:

Do you intend to use compression packings or mono packings? do you know what brand to use? chesterton is th best brand in this mechanics opinion.

The more bronze wear surface the better as it will strengthen the cylinder wall reducing the total stress on the piston, piston rod, stuffing box,

The cylinder piston can be one piece or two pieces bolted together and it must have an o-ring groove to seal the oil flow and eliminate leaking between both oil circuits in the cylinder.

How many mono packings per side do you want in the piston? 1, 2, 3, 4, 5?, you must have the same number of packings on both sides of the piston.

With this type of weight load you will need velocity fuses in the return oil path for the cylinder in case of a hose failure and deceleration valves for the return oil flow which will regulate the downward speed of the cylinder.

If possible obtain a Rukker Yuken hydraulic catalog as it will have all the formulas needed.