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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

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.

Save this run, and compare

Keeps what is on screen so you can change something and see both sides of the change. Saved in this browser only, never uploaded.

Save this as evidence

Collects what you entered, what came out, how it was worked out, and anything the tool flagged, with a timestamp and a version so someone else can reproduce it.

This is evidence, not a notebook entry. It deliberately does not write your problem statement, your reasoning, or your conclusion, because under RECF rules an Engineering Notebook has to be the students' own work and no tool may generate or organise its content. Take the numbers, decide what matters, and write it yourself.