Hiscox movement 230 shows a Brotherhood-type three-cylinder steam engine. Steam enters a central chamber at equal pressure on three pistons, while a crank-pin-operated rotary-disc valve alternately admits steam to the outside of the pistons through separate cylinder ports.
Three-cylinder Engine Interactive Calculator
Enter the first two displayed angular sectors. The calculator closes the circle with a third sector and compares the three with equal 120-degree spacing; it does not model valve timing, steam events, force or output power.
Equation Used
- The three displayed radial directions partition one 360-degree circle.
- Equal illustrative spacing is 120 degrees.
- The source mechanism is represented schematically, not dimensionally.
- Piston motion, rotary valve ports, pressure, expansion, torque, speed, balance, lubrication and efficiency are omitted.
Brotherhood-type Radial Steam Arrangement
Gardner D. Hiscox describes movement 230 as a three-cylinder engine of the Brotherhood type. Steam is admitted to a central chamber with equal pressure on all three pistons.
A rotary-disc valve operated by the crank pin admits steam alternately to the outside of the pistons through an outside port to each cylinder. The main-shaft bearing uses a stuffing box.
What This Explanatory Calculator Does
The tool partitions a displayed 360-degree circle into three sectors and compares them with equal 120-degree spacing. This helps read the conceptual radial diagram.
It is not a thermodynamic cycle, valve-timing, firing-order, balance or performance calculator.
Displayed Angular Partition
largest = max(phi12,phi23,phi31)
departure = max(|phii-120 degrees|)
Sector count is the number of displayed geometric sectors. It does not count steam admissions or power strokes.
Worked Display Example
For phi12 = 120 degrees and phi23 = 120 degrees, the closing sector is 120 degrees, the largest sector is 120 degrees and maximum departure from equal spacing is zero.
This is equal display spacing, not a performance or valve-timing claim.
Model Boundary
- Historical arrangement: Brotherhood-type three-cylinder steam engine with central chamber and crank-pin-operated rotary-disc valve.
- Calculated: closure of three displayed angular sectors and departure from equal 120-degree spacing.
- Not calculated: crank throw, piston displacement, valve port timing, admission, exhaust, pressure, expansion, force, torque, power, speed, balance, bearing load, stuffing-box leakage, efficiency or safety.
Frequently Asked Questions
Is this an inline three-cylinder engine?
No. Hiscox movement 230 is a radial Brotherhood-type steam arrangement.
Does three sectors mean three power strokes per revolution?
No. Sector count describes the diagram’s geometry; the calculator does not model valve timing or count steam events.
Why compare with 120 degrees?
Three equal directions around a circle are separated by 120 degrees.
Does the calculator model the rotary valve?
No. The valve is shown conceptually but its port timing is not calculated.
Are the entered sectors historical dimensions?
No. They are display geometry.
Can this predict engine output?
No.
References
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