Single-speed reduction replaces multi-gear shifting — and that changes what matters in the gear itself: noise, accuracy and surface quality move to the top of the list.
2026-10-12 · База знаний
A conventional gearbox shifts between four to sixteen ratios; an electric drive usually keeps one fixed reduction. Mechanically that sounds simpler, and it is — fewer gears, fewer synchronisers, no clutch packs. But removing the shifting also removes the masking effect of engine noise and of constant speed changes, so every characteristic of the remaining gears becomes audible and measurable.
Three requirements tighten immediately. First, transmission error: because the motor spins to 12,000–16,000 rpm, the same tooth-to-tooth deviation that is acceptable at 2,000 rpm produces a whine at high frequency. Gear accuracy grades that were comfortable in a truck gearbox are no longer enough, and tooth flank modification has to be designed rather than inherited.
Second, contact patterns must survive torque that arrives instantly. An electric motor delivers full torque from zero speed, so the gear sees shock loading on every start. Forged blanks with continuous grain flow along the tooth root handle this far better than cut-from-bar gears, which is why precision forging has become standard practice in NEV reducers.
Third, cleanliness and heat. Higher efficiency targets mean lower oil volumes, so the gear set has to run cooler and cleaner. Controlled carburising, tighter case depth tolerance and a proper post-grinding wash are no longer optional — they decide whether the unit passes the noise audit at the end of the line.
