Pneumatic Cylinder Force

Reference data and engineering information about pneumatic cylinder force for gases and compressed air applications.

Overview

Engineering reference data for Pneumatic Cylinder Force in gases and compressed air.

$PV = nRT$

Pressure × Volume = moles × gas constant × temperature.

$P_1 V_1 = P_2 V_2$

At constant temperature.

$\frac{V_1}{T_1} = \frac{V_2}{T_2}$

At constant pressure.

A single acting cylinder uses compressed air on one side of the piston only. The force is calculated using the full bore area:

$F = p \cdot A = \frac{p \cdot \pi \cdot d^2}{4}$

Example: A single acting cylinder with 1 bar gauge pressure ( $10^5 \text{ N/m}^2$ ) and 100 mm bore diameter:

$F = \frac{10^5 \cdot \pi \cdot (0.1)^2}{4} = 785 \text{ N} = 0.785 \text{ kN}$

Double acting cylinders use compressed air on both sides of the piston, with a rod on one side.

Outstroke (pushing): Uses the full bore area — same formula as single acting cylinder.

Instroke (pulling): The piston rod reduces the effective area on the rod side:

$F = \frac{p \cdot \pi \cdot (d_1^2 - d_2^2)}{4}$

Where $d_1$ is the full bore diameter and $d_2$ is the piston rod diameter.

Example: A double acting cylinder with 1 bar, 100 mm bore, and 10 mm rod diameter:

$F_{\text{instroke}} = \frac{10^5 \cdot \pi \cdot ((0.1)^2 - (0.01)^2)}{4} = 778 \text{ N} = 0.78 \text{ kN}$

Instroke capacity is always lower than outstroke capacity due to the reduced pressurized area from the piston rod.
Always size cylinders based on the minimum force direction (typically instroke) when both strokes perform work.
Gauge pressure (relative to atmospheric) is used in all calculations — not absolute pressure.