# Problem: Extending and Retracting Forces

What are the extending and retracting forces?

##### See the Solution

We have a cylinder that is used where we need extra force, but we don’t have room for a large diameter. If you notice the plumbing going to the cylinder, we are pressurizing one cap end area and one effective rod end area. That is the area below the blackened area in the cylinder. Retraction is the same as a normal cylinder.

Extension – We have two areas to deal with. The cap end area is 4 squared x 0.7854 or 12.57 sq. in. The additional annular [effective rod end area is 12.57 – 3.14 (rod area) or 9.43 sq. in.] Adding 12.57 + 9.43 = 22 sq. in.

F = PA, therefore, 100 x 22 = 2200 lbs. for extension.

Retraction – Annular area is 12.57 – 3.14 = 9.42

100 x 9.42 = 942 lbs. for retraction.

### Deadline past. Not available for submissions.

Winner: John Krebsbach, Fluid Power Engineering, Inc., Milan, IL

Answered Correctly: Richard Throop, Neff Engineering, Flint, MI

Thomas Guidera, Hennepin Technical College, Eagan, MN

Nick Berge, Hennepin Technical College, Waverly, MN

By Ernie Parker, AI, AJPP, AJPPCC, S, MT, MM, MIH, MIP, MMH, Fluid Power Instructor, Hennepin Technical College, EParker@Hennepintech.edu

This teaser is printed in the Fluid Power Journal. Those who submit the correct answer before the deadline will have their names printed in the Society Page newsletter and in Fluid Power Journal. The winners will also be entered into a drawing for a special gift.

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