Simple hydraulic cylinder question

[carter213]

I've got a fundamental hydraulics question that should be easy to answer.

Is a given hydraulic cylinder able to apply more force while extending than while retracting? If so, is there a standard push/pull ratio?

 

[hydtools]

If the cylinder has one rod, the push force is more than the pull force. Subtract the area of the rod from the total piston area to get the effective pull or retract area. Multiply the areas by the pressure to get the push force and the pull force.

No standard push/pull ratio.

Ted

 

[IceStationZebra]

To expand on Hydtools

- If you have a double rod cyclinder the forces are equal. These are not very common, with the big exception being steering cylinders on off-road machinery.
- The reason there is no standard push/pull ratio is that the rod diameter is generally based on the needed buckling strength. And the buckling strength is based on rod length and force applied to the cylinder. And the force could be externally generated and thus higher than the hydraulic force.

ISZ

 

[automatic2]

cylinders made specifically for regen applications may have a larger rod.

 

[hydromech]

Displacement cylinders have no annulus at all..!

 

[budt]

Take a look at Chapter 15 in this Basic Fluid Power Book on the Hydraulics & Pneumatics magazine site. It will give you some ideas on construction and sizing of cylinders and other Linear and Rotary Actuators that are available.

http://www.hydraulicspneumatics.com/200/eBooks/

Bud Trinkel, Fluid Power Consultant
HYDRA-PNEU CONSULTING