This is the same gear-train reduction as the 2D diagram, but built as an actual meshed 3D mechanism: three spur gears with real involute-style teeth spin on fixed axles, each tooth physically passing between the teeth of its neighbour. Because the driver and driven gears mesh through a shared idler, all three gear axes rotate — a real axle-and-mesh assembly, not a flat two-value diagram.
ω₂/ω₁ = N₁/N₂, ω₃/ω₂ = N₂/N₃ ⇒ ω₃/ω₁ = N₁/N₃
tooth-mesh rate = ω₁·N₁ / 2π (teeth passing per second, equal at every mesh point)
- Input speed — angular velocity fed to the driver axle; every other axle's spin is derived live from the tooth ratios, not pre-animated.
- Driver / Driven teeth — resizing either gear changes its physical radius (teeth are placed at a fixed module, so more teeth means a visibly larger gear) and the overall N₃/N₁ reduction.
- Load torque — resisting torque at the output shaft; shown as a torque-arrow scaling on the output axle and a mesh-force glow.
- Mesh contact glow — highlights the tooth pairs currently in contact at each mesh point, the same tooth-passing frequency on every meshed pair (conservation of tooth-mesh rate along the train).
Real-world relevance: this is literally how a gearbox is built — real gears on real shafts, sized so their pitch circles are tangent at the mesh line — the geometry that a torque/speed diagram only summarizes.