How to Select a Conveyor Gearmotor

Published August 13, 2026 · Reviewed by SMK Transmission

A conveyor gearmotor combines an electric motor and speed reducer into one drive package. Its job is to deliver the output speed and torque required at the conveyor drive shaft. Correct selection improves starting reliability, operating temperature and service life; incorrect selection can cause slow acceleration, nuisance trips, overheating or premature gearbox wear.

1. Collect conveyor data before choosing a motor

The gearmotor cannot be selected reliably from conveyor length or motor kW alone. Start with the driven machine and record the actual operating conditions.

2. Calculate conveyor output speed and gearbox ratio

If conveyor linear speed and drive pulley diameter are known, estimate pulley speed using:

Next calculate the theoretical gearbox ratio:

For example, a 1450 rpm motor and a required conveyor shaft speed of 29 rpm give a theoretical ratio of 50:1. Select the nearest available ratio and recalculate the actual belt speed using the reducer's published output rpm. Use the motor's rated full-load speed rather than synchronous speed.

3. Calculate output torque and motor power

Torque is the turning force at the drive shaft. If the required conveyor pull F and drive pulley radius r are known:

Mechanical power can be calculated from shaft torque and speed:

For a preliminary check from selected motor power:

This calculated value is not permission to exceed the reducer rating. The final combination must remain within the manufacturer's permitted continuous output torque, peak torque, thermal capacity and shaft-load limits.

4. Check startup torque, duty and service factor

A loaded conveyor may need substantially more torque during acceleration than while running. Product accumulation, sticky material, incline, frequent starts and reversing all increase demand. Confirm the motor starting method—direct-on-line, soft starter or variable-frequency drive—and compare the available starting torque with the load requirement.

Service factor accounts for application severity. Operating hours, switching frequency, shock, load inertia and ambient temperature can affect the required factor. Service-factor definitions and ratings are manufacturer-specific, so do not compare a number from one catalog directly with another without checking its basis.

• Light duty: uniform load, limited daily hours and few starts.
• Moderate duty: longer operation, regular starts or varying load.
• Heavy duty: high inertia, shock, frequent starts, reversing or inclined transport.

5. Select gearbox type, shaft and mounting

A worm gearmotor offers compact right-angle transmission, broad ratios and convenient hollow-shaft mounting. A hypoid gearmotor may be preferred where higher efficiency, compact right-angle geometry and long operating hours are priorities. Final choice depends on ratio, torque, efficiency, space, budget and duty.

Confirm solid or hollow output shaft, shaft diameter, key, torque arm, flange or foot mounting, and installation position. Sprocket, belt and pulley drives can apply overhung load to the output shaft; verify this separately. Also confirm lubrication suitability for the mounting position.

6. Conveyor gearmotor calculation example

Assume a conveyor needs 0.20 m/s belt speed and uses a 200 mm drive pulley. The required pulley speed is:

With a motor rated near 1450 rpm, the theoretical reduction ratio is approximately 1450 ÷ 19.1 = 75.9, so a catalog ratio near 75:1 or 80:1 should be evaluated. If the running shaft torque requirement is 120 Nm, the mechanical output power is approximately 120 × 19.1 ÷ 9550 = 0.24 kW.

That does not mean a 0.25 kW gearmotor is automatically correct. Starting torque, acceleration time, efficiency, daily operation, starts per hour, service factor and reducer rated torque still require verification. A higher motor or gearbox size may be needed after these checks.

7. Conveyor gearmotor quotation checklist

For a faster quotation, provide:

• Conveyor type, length and maximum transported load
• Belt speed or required output rpm
• Drive pulley diameter and conveyor inclination
• Running torque and peak torque if calculated
• Operating hours/day, starts/hour and direction
• Motor voltage, frequency and required control method
• Gearbox mounting position and output shaft or hollow-bore dimensions
• Ambient temperature, dust, moisture or washdown conditions
• Required quantity and target delivery date

Explore SMK gear motors, compare worm gear reducers and hypoid gear reducers, or send your conveyor data for selection support.

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