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Pneumatic Reliability

A cylinder that works at full pressure is not the test. This compares setups at the pressures you will actually have late in a match.

Inputs

One row per setup and pressure. The point is to test the same mechanism at high and low pressure, because that is the difference between the first actuation of a match and the last.

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Results

Most reliable setup

—

Its success rate

—%

95% range

—%

Worst at low pressure

—

Reliability lost from high to low

—pts

Most common failure

—

Attempts recorded

—

Setup by setup

SetuppsinSuccess95% rangeForce vs 100 psiWorst failure

Let the tank run down

Let the tank run down
100 psi

Every setup you tested, placed at the pressure you tested it at, with its success rate and the 95% range around it. Slide the pressure down the way a match does and read off the nearest test you ran. Nothing is filled in between tests: if you never tried a pressure, the page says so rather than guessing.

How this is calculated

Cylinder force falls in direct proportion to pressure. At100 psi a VEX cylinder pushes about54 N. At half that pressure it pushes half as hard, and a mechanism with no margin stops working somewhere in between.

force ≈ 54 N × (pressure ÷ 100)

So the honest question is not whether a mechanism works, but the pressure at which it stops working, and whether the match ends before you reach it. Testing only on a freshly charged tank answers neither.

Read the failure modes

  • Too slow usually means restricted flow rather than insufficient force: narrow tubing, a long run, or a fitting throttling it. It tends to appear before the mechanism fails outright.
  • Did not hold means force ran out. The cylinder moved but could not keep its grip against load, which is the classic low pressure symptom and the most dangerous one, because it works in testing and fails under game conditions.
  • No motion is usually electrical or mechanical rather than pneumatic: a solenoid not firing, a jammed mechanism, or a disconnected line. Pressure is rarely the cause.

Same statistics as everywhere else

The 95% ranges are Wilson score intervals, and the same rule applies:overlapping ranges mean you have not told two setups apart.Twenty-five trials at each of two pressures is a reasonable afternoon and enough to see a real difference.

What good looks like

A mechanism that holds its success rate from full charge down to the pressure where you would call the tanks spent. If reliability falls off a cliff at 60 psi, you do not have a mechanism that works with a caveat, you have one that works for the first half of the match.

Sources & assumptions

The 54 N extend force at100 psi and the 10 mm bore are VEX published figures. Force at other pressures scales linearly from those, which follows from force being pressure times area.

Retract force on a dual acting cylinder is lower than extend force, because the rod takes up part of the piston area. VEX does not publish the rod diameter, so this tool does not model the difference and treats both directions as using a full bore of air, which is slightly pessimistic on air and optimistic on retract force.

Ranges are 95% Wilson score intervals, which assume attempts are independent and consistently conducted. They cannot account for a mechanism that warms up, wears in, or is being tested by someone who has got better at it over the afternoon.

Every source the site uses, and when it was checked

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                                Comes after

                                Match Air Budget Calculatorgives you your air pressure

                                You are here

                                Pneumatic Mechanism Reliability

                                Where your answer goes

                                Compare Test Versionstest whether one setup is really better or it was just luckuses your trial results againMatch Air Budget Calculatorsee if the pressure drop hurting it is just running out of airuses your air pressure againCylinder Force Calculatorsee how much force you lose at the pressure where it failsuses your air pressure againEndgame Timingweigh whether to risk an endgame that sometimes does not fireuses your success rate again

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