single or double acting cylinder

admin

hey all,looking at building an H frame press...50t. looking to use spx power team gear. I have heard conflicting info regarding single and double acting cyclinders.Regarding the return of the ram after pressing, will a single acting cylinder return when mounted verticaly as in the press??? I ask this becasue a rep form enerpac said that anything over 30t mounted vertically as in a press will take forever to return by itself?? But looking at enerpac and SPX websites they both offer a 50t press with basic hand pump and single acting cylinder....My press will be for me not making $$$ so it doesnt need to be a hi speed producting unit...just want good qualityAlso can I use the hand pump for a double acting cylinder on a single acting cylinder?cheers,Serg
Reply:Single action will work just fine with the addition of springs to return the cylinder. Many presses are made this way and it is the cheapest way to go. If you want to do it on the cheap $$$ use a bottle jack with spring return. I have seen bottle jacks on Craigslist really cheap.
Reply:Most press cylinders are single-acting with spring-return, using an internal spring.For economy's sake high pressures requires small ports and hoses. Small ports and hoses are restrictive and thus slow to return fluid in volume, especially when cold.I know of a large press that has a small "ladder" hanging from the frame.If the operator is a big hurry for the ram to return, she can help it along by using a pinch-bar between a ladder rung and the ram. Yes, on using the hand-pump with a single-acting cylinder.Good Luck
Reply:thanks guys,so when you have pressed and have released the pressure, the fluid from the cylinder is now returning back to the pump???although Im looking at the 13 inch stroke cyclinder from SPX I dont think its going to be a case of waiting for it to return the full 13 inches...it will only have to return enough to remove the work piece....giving it a little help should not be too hard.I already have a SPX air/hyd pump and 10t long stroke cylinder with my JD 4 bender. So commonality is someting im trying to keep.Looks like I ll be able to get the pump's shipped to Oz no worries, but the cylinder is another problem...The reason Im looking at the pump for double acting cylinders, is that it isnt that much more to buy compared to the single and It could come in handi down the track......does anyone know if USPS still offer the old surface mail, ie by ship? the 50t cylinders exceed their weight for all standard (international) services which are air cheers,Serg
Reply:I personally would make a double acting press if it wasn't that much more. We have a 100 ton press at work and it drives me insane waiting for it to return, and I'm getting paid.AllenSA-250LN-25Smith heavy duty OABobcat 250 at workMiller 210 at work
Reply:the double acting cylinders are quite a bit more expensive, at least 50% more....considering a good 50t single acting cylinder isnt going for less than $1000 we are talking some coin...