Brown's movement 87 reverses one shaft mechanically: two opposite-running loose bevel gears flank a sliding clutch, while a shaft-driven stud wheel trips a bell-crank and weighted over-center lever to engage the opposite gear.
Ideal Self-Reversing Bevel/Clutch Timing
Explore ideal reversal timing for Brown's loose-bevel-gear and sliding-clutch mechanism.
Equation Used
- Forward and reverse shaft-speed magnitudes are equal.
- The selected output revolutions per trip remain constant.
- Clutch transfer is instantaneous with no overlap or dwell.
- Dynamics, impact, torque capacity and wear are excluded.
Output revolutions per reversal is a selected effective ratio between shaft rotation and successive stud trips.
Alternating clutch selection
The bevel gear between B and C is the driver. B and C run loose on the output shaft until sliding clutch D locks one of them to the shaft. Wheel E then turns with the shaft; its stud trips bell-crank G, carrying weighted lever F past center so it snaps the clutch into the other gear.
The former diamond-groove leadscrew explanation described a different mechanism and is removed.
What the calculator determines
Select ideal output-shaft speed magnitude N and the output revolutions n required for wheel E to reach each trip. The calculator reports time between reversals, full forward/reverse cycle time, reversals per minute and complete cycles per minute.
Ideal reversal timing
At constant speed magnitude N, one output revolution takes 60/N seconds. Therefore trev = 60n/N and tcycle = 120n/N. Reversal frequency is N/n per minute and complete-cycle frequency is N/(2n).
Selected-input arithmetic
At 600 rpm and one output revolution per trip, the shaft reverses every 0.1 s, completes a forward/reverse cycle every 0.2 s, and produces 600 reversals or 300 full cycles per minute.
Model boundary
This ideal timing model assumes equal speed magnitude in both directions and instantaneous clutch transfer. The animation preserves continuous opposite rotation of the loose gears, but the trip-wheel, bell-crank and weighted-lever positions are qualitative topology rather than a dimensionally closed linkage reconstruction. Bevel ratios, trip-wheel gearing, stud dwell, over-center dynamics, clutch overlap, backlash, impact, inertia, torque capacity, lubrication and wear are not calculated.
Questions
Do gears B and C rotate together?
They rotate oppositely and remain loose until clutch D engages one.
Why does the shaft reverse?
The clutch transfers connection from one oppositely rotating gear to the other.
Is shifting instantaneous in hardware?
No; that is an explicit idealization in this timing reference.
References & Further Reading
- Wikipedia contributors. Reciprocating motion. Wikipedia
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