For a selected uniform gauge pressure p acting normally over an ideal circular port of diameter d, projected area is A = πd²/4 and resultant pressure force is F = pA. This force is not a trunnion-spring preload recommendation.
Selected Circular-Port Pressure Load
Calculate radius, circular projected area and ideal normal pressure resultant from selected pressure and port diameter.
Equation Used
- Pressure is uniform and acts normally on the selected circular projection.
- Entered pressure is gauge pressure relative to the opposite side.
- The circular diameter is exact for the selected projected area.
- Full geometry, sealing, friction, dynamics, losses and ratings are excluded.
The animation is illustrative oscillating-cylinder topology and does not define real port timing or dimensions.
Oscillating-cylinder topology and selected load
An oscillating cylinder pivots as its piston rod follows the crank, allowing a cylinder passage to align alternately with fixed inlet and exhaust passages. The animation shows this qualitative relationship.
The calculator is narrower: it applies selected uniform pressure to one ideal circular projected area. It does not model the full port face, cylinder bore, steam cycle, friction or sealing interface.
What the calculator determines
Select gauge pressure and circular port diameter. The calculator returns radius, projected area, pressure in kilopascals and the ideal normal resultant pA.
It does not determine required spring preload, contact pressure, sealing margin, friction, admission, exhaust, mean effective pressure, torque, power, speed, leakage, wear or safe operation.
Projected pressure-load identity
Radius r = d/2. Circular projected area A = πd²/4. Pressure conversion is 1 bar = 100 kPa = 0.1 N/mm². Therefore F = pA, with p in N/mm² and A in mm².
A real retaining or spring force requires the complete pressure-loaded geometry, contact and friction model, dynamics, tolerances and a defined safety basis. No universal multiplier is supplied.
Selected-input example
At 4 bar and 2 mm diameter, radius is 1.000 mm, projected area is π mm², selected pressure is 400 kPa and the ideal normal resultant is about 1.257 N.
This is the pA load on the selected circular projection only; it is not a recommended spring force or proof of sealing.
Scope and correction boundary
The former calculator multiplied pA by arbitrary factors of four and twelve and presented the results as a recommended clamp range. Those multipliers were not derived from a complete joint, friction, sealing or dynamic model and are removed.
Unsupported speeds, pressures, tolerances, spring forces, products, failure diagnoses, maintenance instructions and performance claims, the fabricated launch example and unrelated video are also removed.
Questions
Is pA the required trunnion spring force?
No. It is only the ideal resultant on one selected circular projection.
Does the calculation include cylinder-bore pressure load?
No. Only the entered port diameter defines the area.
Can it predict leakage or friction?
No. Surface geometry, flatness, contact pressure, material, lubrication, temperature and motion are not modeled.
Does the animation establish port timing?
No. It is illustrative topology without dimensioned port locations or timing events.
Technical references
- OpenStax Physics, Pressure — pressure as normal force divided by area.
- NIST Special Publication 811 — SI units and pressure conversions.
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