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Push and pull with a pneumatic cylinder

One cylinder can have different pushing and pulling forces. Define the required force first, then check pressure and effective areas.

Axial cylinder sections with extension above and retraction below, bore and rod dimensions, pressures and output force directions.ppbFextExtensionpbpFretRetractionDd
Axial sections of a double-acting single-rod cylinder: extension above and retraction below. Blue p is supply; pb is exhaust back pressure. Red Fext and Fret are output forces.

What you will understand

  • Different effective areas for push and pull
  • How supply, back pressure and losses affect force
  • Separate thrust, speed and final selection

Blue: defined conditions · Red: calculated quantities. Diagrams are schematic.

  • D: bore, d: rod diameter
  • p, pb: gauge pressures with the same ambient reference
  • Fext, Fret: extension and retraction thrust

The examples below are illustrative. Each example button loads its fixed values, units and mode. Ordinary calculator links do not load an example.

Define the load and direction

Define push/pull direction, orientation, acceleration and contact resistance. Do not enter mass in kg as force in N. Lifting also needs gravity and acceleration forces.

  • Moving mass, orientation, external load and guide/seal resistance
  • Stroke, travel time and stopping method

Separate areas and pressures for each direction

During extension supply acts on full area A₁ and back pressure on annular area A₂. Retraction reverses them. Use running pressures near the cylinder, not only the upstream regulator setting.

For practical review

For each direction p denotes the supplied chamber and pb the exhausting chamber. This quasi-static comparison uses the same pressures and loss for both directions; actual values can depend on direction and speed. Use condition-specific losses rather than a universal percentage.

A₁=πD²/4, A₂=π(D²−d²)/4 / Fext=pA₁−pbA₂−Floss, Fret=pA₂−pbA₁−Floss

Compare both thrusts with demand

Read thrust minus requirement separately for each direction. A positive difference is not final approval; a negative one means the entered requirement is unmet.

Example: can both directions meet 500 N?

Inputs

  • D=40 mm, d=16 mm
  • p=0.5 MPa, pb=0.05 MPa, Floss=20 N
  • Required Freq=500 N (illustrative)

Results

  • Extension Fext≈555.540 N → difference +55.540 N
  • Retraction Fret≈444.956 N → difference −55.044 N

Retraction falls short of the same 500 N requirement. Positive extension margin does not establish load ratio, speed, side load, buckling or stopping suitability.

Load the fixed values, units and mode for this illustration. Then edit them for your conditions.

Check flow, speed and stopping

Producing force does not establish travel time. A larger bore also needs more flow for the same speed. Review end-stop impact and possible falling on supply loss separately.

  • Piping/valve flow, back pressure, stroke and actual travel time
  • Cushion, external stop, guide and rod buckling
  • Holding and fall prevention on stopping or loss of pressure

Keep a review checklist

This checklist is a personal reminder, not a safety score or an automatic approval. It is not sent or saved.

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Reference information and illustrative calculations. This content does not guarantee suitability or safety of a design. Confirm the actual materials, component specifications and operating conditions.