A two-speed transmission provides two selectable fixed ratios. In the illustrated dog-clutch topology, two continuously meshed gear paths turn at different speeds and an axially sliding jaw-clutch member selects which path transmits torque.
Two-Speed Gear Interactive Calculator
Enter ideal reduction ratio A and ratio B. The tool reports the ideal torque ratio and output/input speed ratio for each path; it does not predict efficiency, tooth loads, shift behavior or hardware ratings.
Equation Used
- Both entries are positive ideal speed-reduction ratios.
- Each path is evaluated independently; the tool does not require one ratio to exceed the other.
- The torque ratio assumes ideal lossless power transfer.
- Only one path is illustrated as selected at a time.
- Tooth counts, module, center distance, contact ratio, efficiency, inertia, backlash, lubrication, shift timing, synchronizers, forces, stress, wear and suitability are omitted.
Two Gear Paths and One Selector
U.S. Patent 3,091,975 describes a two-speed arrangement with two gear paths that rotate driven members at different speeds. A slidable jaw-clutch member between torque-transmitting members moves axially to engage teeth on one side or the other, selecting the transmitted path.
What This Calculator Represents
The tool compares two independently entered ideal reduction ratios. The animation shows both gear paths while the collar alternates between path A and path B. It is not a dimensioned gearbox or shift simulation.
Ideal Ratio Arithmetic
output/input speed ratio = 1/R
ideal lossless torque ratio = output torque / input torque = R
MIT mechanical-design notes express gear-train power as input torque times input angular speed and output torque times output angular speed. Equating those products gives the ideal torque relation; real losses are excluded here.
Worked Ideal Example
For entered ratio A=20:1, the ideal output/input speed ratio is 0.050 and the ideal lossless torque ratio is 20. For entered ratio B=4:1, the corresponding values are 0.250 and 4. The ratios are independent entered cases.
Model Boundary
- Mechanism: two different-speed gear paths and an axially sliding jaw clutch that selects either side.
- Calculated: ideal speed and lossless torque ratios from entered reductions.
- Not calculated: tooth counts, module, pitch diameter, center distance, contact ratio, efficiency, power, actual torque or speed, tooth force, bearing load, inertia, acceleration, backlash, shift dynamics, synchronization, stress, temperature, wear, life, controls or suitability.
Frequently Asked Questions
Must ratio A be larger than ratio B?
No; the calculator evaluates the two entered paths independently.
Does a 20:1 entry guarantee twenty times the real torque?
No; that value is an ideal lossless ratio.
Are tooth counts calculated?
No.
Does the collar animation simulate engagement?
No; it only indicates which ideal path is selected.
Are neutral and simultaneous engagement modeled?
No.
Can this size a gearbox?
No.
References
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