Fluid Power Calculators

Fluid power calculators turn pressure and piston geometry into extend force, retract force, or suggested bore size. The physics is F = P × A: full bore area on extend, annular area on retract when a rod takes up space on the cap side.

Three tools cover the usual actuator questions on TaskJunction. Pneumatic Cylinder Force targets shop air systems. Hydraulic Cylinder Force targets oil-hydraulic pressures. Hydraulic Cylinder Selector works backward from required push force to a bore recommendation with a safety factor.

Single-rod cylinders pull harder on extend than retract. That matters on clamps where retract must clear the part and extend must hold against cutter load. Double-rod designs balance the areas, but most fixtures and presses use single-rod units.

Fixture design often starts with a force target: hold this part against a 2 kN milling load at 6 bar shop air. Catalog pages list bores, but you need to know if 40 mm is enough before you burn a mounting plate.

On the floor, weak motion might be low pressure, worn seals, or an oversized rod eating retract area. A force check separates mechanical limit from valve or flow problem.

Intensifiers downstream of the pump can exceed nominal system pressure at the work port for short strokes. Enter the pressure the piston sees during the hold portion of the cycle, not the standby gauge reading.

• Extend versus retract on the same bore and rod
• Whether available pressure meets a clamp or lift target
• Bore screening from force and system pressure
• Replacement cylinder check against nameplate geometry

Enter gauge pressure and diameters in the form units. Extend uses π/4 × bore². Retract uses π/4 × (bore² − rod²). The selector applies your safety factor before solving bore. Symbol layout on schematics follows ISO 1219 conventions common in fluid power documentation.

Shop air at 6 bar is not 6 bar at the cylinder after a long line and a undersized FRL. Measure at the port when results disagree with floor observation. Rod buckling and side load on long strokes are outside these forms but often show up when retract force looked fine on paper.

Sequencing matters on real machines. A clamp may need full extend force before the tool engages, while retract only needs enough stroke to clear the part. Toggle and link clamps change the mechanical advantage between cylinder and pad.

Mobile equipment adds rod port sizing and flow limits that static force does not address. Still, if extend force at working pressure cannot overcome the worst-case load, no valve tuning fixes the bore.

• Pneumatic tool for air, typically lower pressure and smaller bores
• Hydraulic force tool for industrial oil pressures
• Selector when force and pressure are known but bore is not
• Run extend and retract on one form before fixing rod diameter

Open these during fixture layout, automation concept, actuator troubleshooting, or actuator homework. You need either known geometry and pressure, or known force and pressure for bore selection.

Rodless cylinders and cable cylinders spread force across a different area definition. Map catalog effective area into the bore field or use a dedicated vendor worksheet when geometry is nonstandard.

Intensifiers and pressure boosters change available pressure at the work port. Enter the pressure the piston actually sees, not the pump standpipe gauge, when those devices sit in the line.

Pick-up applications with vacuum cups still need enough extend force to break the seal. Retract must clear the nest before the next part advances. Run both sides of the force check before you size the valve bank.

Beam supports and motor torque for the same frame belong in Mechanical Calculators. Feeds for the part in the fixture are under Machining & CNC on the site.

• Clamp and press fixture sizing
• Shop air adequacy for a new pneumatic unit
• Class problems on cylinder areas
• Not for certified lifting without full standards review
• Regenerative extend circuits need manual area adjustment to match real plumbing

Shop air at 6 bar is not 6 bar at the cylinder after a long line and undersized FRL. Measure at the port when results disagree with floor observation. Rod buckling and side load on long strokes are outside these forms but often show up when retract force looked fine on paper.

• Gauge pressure at the port, not absolute unless the form says so
• Bore and rod diameter from catalog or caliper
• Required extend force if using the selector
• One unit system end to end on the form
• Rod seal friction margin when pressure is borderline

Shop air and known bore: Pneumatic Cylinder Force Calculator. Hydraulic system with the same known geometry: Hydraulic Cylinder Force Calculator. Known force and pressure, unknown bore: Hydraulic Cylinder Selector Calculator. When extend and retract both matter on a clamp, run the same bore through both directions before you order the rod diameter.