Explore a universal (Cardan) joint for mechanical shaft-drive design. Changing the shaft angle makes the output speed up and slow down even with a constant input. Watch the white rotation marks together with the speed chart.
Example buttons set both A and B. Both models share one clock and one scale. Change each condition in its own input fields.
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Play to rotate the shafts at the entered rpm.
At high speeds, frame sampling can make rotation look reversed or stationary. No automatic slowing is applied. Reduce the playback multiplier to inspect motion.
Angles above 45° are kinematic comparisons. Actual joints may not accommodate this angle.
Solid: output / input. The vertical line is the current input angle. Both charts share the same vertical scale.
Solid: output / input. The vertical line is the current input angle. Both charts share the same vertical scale.
Even with constant input speed, the white output mark can speed up and slow down. Use the min–max range and speed chart alongside the instantaneous value.
At θ=0°, the input cross pin points upward in the model. A different phase reference shifts the waveform but does not change its minimum or maximum ratio.
Input and output shaft lengths are 110 mm each; double-joint centre spacing is 160 mm. A and B use the same dimensions. These lengths do not affect the speed ratio.
Rigid-body kinematics with coplanar shaft axes. Ripple is (maximum ratio − minimum ratio) × 100%. The mean output speed equals the input; this is not a reduction gear. Friction, play, inertia, vibration, life and actual-part interference are excluded. Input ranges are not product ratings.
φ = atan2(cos β · sin θ, cos θ)
ωout / ωin = cos β / (1 − sin²β · sin²θ)Angles are unwrapped across complete turns.