Hydraulic cylinders 101

[powerscol]

I am trying to choose the correct cylinder for my sickle mower lift conversion. From another post I know the dimension and brand previously used and I confirmed the movement and fit on my mower today using a pvc mock up . Its a Tractor Supply unit rated at 2500 PSI

From my Bobcat owners manual it states System Relief at quick couplers is 2611 psi.

From this information will this cylinder work, or do I need to find one rated for a higher PSI? They do exist through several sources.

Also it appears the hoses I need should be rated at 3000 psi or higher, correct?

Thanks from an old guy still learning.

 

[Jim Timber]

The "textbook" answer is you need to meet/exceed the working pressure potential with all of your components ratings.

In this instance, the chances of having problems are quite low as that's a very minor discrepancy in the cylinder's rated PSI and the actual system pressure (assuming it's actually making that pressure now? Have you checked it?). There's also probably a safety factor on cylinder construction/ratings that I'm not aware of, so it won't "explode" or blow the seals out the instant you reach 2501 psi. You also wouldn't be likely to ever reach the operating limit of your cylinder in your application unless you held the valve open while the travel stops had been reached.

You want 3,000 psi hoses.

 

[powerscol]

Thanks for the help.

 

[IceStationZebra]

I agree with Jim and will add that hydraulic components are usually rated for a burst pressure that is at least 3x the rated pressure.(Not sure about NPT or brass fittings, generally shy away from them.) This is kind of like the fuel reserve on board an aircraft though, as an engineer I'm not allowed to utilize that capability except in extreme circumstances.

"I've got a ten minute reserve... but I'm not allowed to invade that except in time of war." Helicopter pilot to Jack Ryan in Clear and Present Danger

ISZ

 

[robpm]

"I've got a ten minute reserve... but I'm not allowed to invade that except in time of war." Helicopter pilot to Jack Ryan in Clear and Present Danger

ISZ

I thought that was "Hunt for Red October"

 

[SSdoxie]

I have one of those 2500 psi TSC cylinders on my grapple. I hit relief evey time I open or close it. Been doing this for about 1 1/2 years. So far have only manged to break loose the cylinder mount at the bucket due to crappy weld. No problems with the cylinder. My relief tests 2660 psi.

 

[powerscol]

Well I decided to do this correct and I ordered the Rowse kit. A little more pricy, but it gives me extra down range to cut ditch banks. Also in checking dimensions, I could put the cast connection point on the head into a bind, an expensive fix.

However it has a single acting cylinder, so I have a question. In reading my manual it indicates when you move the lever from A to be, B is flow, and A is return. So if I plug into A, leaving B unused, will A bleed off backwards if I move the lever towards B to release pressure on A. I know I will be pumping against a dead port.

Thanks Keith

 

[J_J]

Yes, your pump will pump against the relief valve for a mew moments.

You plug one of the work ports.