Sourcing gearboxes and drive parts from China

Duty by component

Read from the UK Trade Tariff on 25 September 2026, gear boxes and other speed changers, spur, helical, bevel and worm gears, ball screws, pulleys and flywheels of cast iron or steel, and clutches and shaft couplings carried 0% duty on goods from China. Transmission shafts carried 4% and bearing housings incorporating bearings 6%. No line carried an anti-dumping measure.

A drive assembly may be classified as a gearbox, as a motor with a gearbox, or as parts, so confirm the commodity code for the form in which it arrives; geared motors are covered with electric motors. For railway applications, see our guide to sourcing rolling stock parts.

Ratings are the specification

A gearbox is specified by rated torque, ratio, input speed, service factor, mounting and shaft arrangement. Give the factory the load and duty cycle, not only a catalogue number, and ask for the datasheet and a load test on a sample; a cheaper gearbox with the same dimensions often has a lower rating.

For replacements, the mounting dimensions must match the unit being replaced; send drawings or the original part number, and check fit on the first samples.

Materials, heat treatment and noise

Gear life depends on the steel, the heat treatment and the tooth finish. Ask for material certificates, hardness readings and gear accuracy grades, and check noise, backlash and temperature rise under load at inspection. Housings are castings, so check for porosity and machining accuracy on bearing seats.

Lubrication at dispatch matters too: some gearboxes ship dry and must be filled before use, which has to be clear on the label.

Worked duty example

Take a hypothetical order of 300 worm gear speed reducers, entered under 8483 40 51 90: £24,000 free on board plus £2,000 of freight and insurance gives a customs value of £26,000. Gearboxes carry no duty, so import VAT of 20% on £26,000, £5,200, is the only tax. A VAT-registered importer normally reclaims it, so the border adds no lasting cost. Step by step: UK import duty and VAT.

Inspection checklist

Rating evidence: ask for the gear load capacity calculation behind the rated torque, for example to ISO 6336, then run a sample at rated torque and speed for the hours agreed in the order and record oil temperature rise against the datasheet limit.

Gears and hardness: check gear accuracy against the ISO 1328-1 grade on the drawing, measure tooth and shaft hardness by Rockwell to ISO 6508-1 on sample parts, and check keyways, shaft diameters and mounting holes with gauges.

Noise and finish: measure airborne noise under load by the method of ISO 8579-1 against the agreed limit, check paint adhesion by cross-cut to ISO 2409 on castings, and check breathers, oil level plugs and the lubrication label on every unit.

What goes wrong

Gearboxes fail on heat, noise and leaks. Worm sets overheat and wear quickly under the real duty cycle because the rating was optimistic, backlash and noise are higher than the datasheet, and oil seals leak from the first week. Housings have casting porosity, cheaper bearings replace the specified brand, ratios or shaft dimensions differ slightly from the drawing, and paint and corrosion protection fail outdoors.

Run samples under load for several hours and record temperature rise, noise and oil leakage, measure backlash and check the ratio, measure input and output shaft dimensions, keyways and mounting holes against the drawing, check the bearing brand and grease or oil type, and inspect castings and paint before shipment.

Continuity of supply

OEM buyers need the same gearbox for years. Ask how long the design will be made, how changes to gears or bearings will be notified, and keep an approved sample. The machinery guide covers the wider category.

Cambridge China Bridge sources gearboxes, gears, pulleys and couplings for OEMs and maintenance buyers, with ratings, materials and load tests checked before shipment. See how our sourcing service works.