Physics
Gear train
Meshing gears: ratios, direction reversal, speed and torque trade-off.
What happens
Meshing gears trade speed for torque at a rate set purely by tooth counts: a small wheel driving a big one turns fast but weak, the big one answers slow but strong, and every mesh reverses the direction. Slip in an idler to fix the direction without touching the ratio, or chain four gears and multiply the ratios.
Equations used in the module
Equations ω₂/ω₁ = −N₁/N₂ |τ₂/τ₁| = N₂/N₁; P = τω m = d/N; m₁ = m₂ (N_s+N_r)ω_c = N_sω_s + N_rω_r x_rack = r_pinion θ_pinion
