Standard hydraulic cylinder sizes

[PNachtwey]

I would like to know if there are any standard hydraulic cylinders sizes ( bore and rod diameter ) for cylinders with bores over 200mm or 8 inches. I have seen tables that go up to 200mm or 8 inches but not greater than that. I know that press cylinders can have much bigger diameters. They must all be custom made or are they?


Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com

http://forum.deltamotion.com/

 

[TimSchrader2]

Hello. The below and others may have them. 8" is mentioned, but I do not believe they are stock. Also, they list a 6" Bore with a 1/4" wall, which we have never seen on our cranes from other suppliers. Although I think 1/4" wall for 6" bore is theoretically possible.

https://www.baileymanufacturing.com/standard--hydraulic-cylinders

 

[PNachtwey]

That didn't help. There was no mention of standard cylinder bores greater than 200mm or 8 inches.
What I am doing is writing a program that will optimize or automate selecting the cylinder bore/diameter. This is the most critical part of a servo hydraulic design. In the past we have had too many customer screw up designs and find their performance criteria cannot be met. The happens frequency with rod up applications. Rod down applications often cavitate when moving down. Sometimes this can be "fixed" by making the cylinder diameters bigger than 200mm or 8 inches. Sometimes this can be "fixed" by using a valve with flow ratios of 2 to 1 but big valves cut 2 to 1 are rare.

Anyway my program seems to work but it limited to 200mm diameter cylinders there aren't any bigger standard cylinders in my table. If I don't get a good answer I will expand the table by 50mm or 100mm increments trying to keep the ratio of the areas constant.


Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com

http://forum.deltamotion.com/

 

[TimSchrader2]

Hello OP

I just pasted the link. If you scroll down to Chief WT 3000PSI you will or can open the pdf that shows the 8" bore that I mentioned. We do not use Bailey and have not looked at thier cylinders for years.

We have used 8-10" Bores with rod down and had no issues. But they move quite slowly and all have a C'bal with a 3;1 ratio for load control.

 

[Compositepro]

To me it seems that relying on oil not to cavitate in order to prevent movement of a hydraulic cylinder, is a flawed and potentially unsafe design. Using a larger cylinder to avoid cavitation is an expensive way to solve the problem. Oil should always be under pressure and not under vacuum.

 

[PNachtwey]

Using a larger cylinder to avoid cavitation is an expensive way to solve the problem. Oil should always be under pressure and not under vacuum.

I agree, right now my program uses 4 loops, criteria, to determine the best cylinder size. The program will not suggest a cylinder size that will cavitate. It is easy to calculate when the cylinder will cavitate. Usually it is due to the piston moving too fast downwards when the rod is pointing down. It will also cavitate when extending a large mass horizontally then trying to stop suddenly. I have these covered. A CBV valve helps solve the hydraulic problem but causes problems when extending but CBV valves cause the actuator to chatter when extending downwards. There is a trade off that must be made but I am only concerned with hydraulic servo applications where CBVs use is not good.


Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com

http://forum.deltamotion.com/