A worm gear motor combines an electric motor and worm gearbox in one drive package. It is commonly used when a machine needs compact right-angle transmission, low output speed, increased torque and straightforward installation. Conveyors, packaging machines, gates, mixers and handling equipment are typical applications.
1. What is a worm gear motor?
The electric motor supplies rotational power to a worm shaft. The worm drives a bronze worm wheel, changing the axis of rotation—typically by 90 degrees—while reducing speed. The integrated package can use a hollow output shaft, solid shaft or flange arrangement depending on the machine.
| Characteristic | Practical meaning |
|---|---|
| Right-angle layout | Motor and output shaft can fit compact machine layouts |
| Single-stage reduction | Common ratios are available in one gearbox stage |
| Smooth operation | Sliding tooth contact can provide relatively quiet motion |
| Modular mounting | Foot, torque arm, flange and hollow-shaft options may be combined |
| Efficiency varies | Ratio, size, speed, temperature and lubrication affect losses |
2. Calculate ratio and output speed
i = ratio, n1 = motor speed in rpm, n2 = required output speed in rpm
For a motor running at 1400 rpm and a machine needing about 47 rpm, the preliminary ratio is 1400 ÷ 47 ≈ 30. Select the nearest available nominal ratio, then use its exact catalog value to confirm output speed.
If the application needs adjustable speed, define the minimum and maximum output rpm and required torque across the range. A variable-frequency drive, UDL mechanical variator or another control method may be appropriate, but gearbox lubrication and motor cooling still require verification.
3. Output torque and service factor
A preliminary output-torque estimate is:
M2 = output torque in Nm, P1 = motor power in kW, η = gearbox efficiency, n2 = output rpm
This formula is not a final gearbox rating. Use the permitted output torque listed for the exact gearbox size, ratio, input speed and duty. Efficiency should come from relevant manufacturer data because worm gearing losses vary significantly with operating conditions.
Service factor accounts for operating time, load type, starts, reversals and shock. A uniformly loaded conveyor and a frequently starting mixer can need different gearbox capacities even when average power is similar. Check continuous torque, starting torque and peak torque separately.
4. Efficiency, temperature and lubrication
Worm drives create sliding contact and heat. Higher ratios and small sizes may have lower efficiency than other gearbox types. Confirm thermal capacity for long operating hours, high ambient temperature or restricted airflow. The correct oil type, fill quantity and mounting position are essential.
During initial operation, temperature and sound should be monitored. A unit should not be assumed defective or acceptable from touch temperature alone; compare measured operating conditions with the supplier's limits.
5. Self-locking and backdriving
Some worm gear arrangements resist backdriving under particular static conditions, but not every worm gear motor is self-locking. Lead angle, friction, lubrication, wear, vibration and external load all influence behavior. Never use assumed self-locking as a personnel-safety brake or load-holding device. Use a properly rated brake or other safety system when uncontrolled movement could cause injury or damage.
6. Mounting, shafts and application environment
- Mounting position: affects oil level and lubrication instructions.
- Output interface: confirm hollow or solid shaft diameter, key, flange and torque arm.
- External loads: calculate radial and axial forces from pulleys, sprockets or screws.
- Motor interface: verify motor frame, flange, power, voltage and frequency.
- Environment: specify dust, moisture, washdown, corrosion, temperature and altitude.
7. Worm gear motor selection checklist
| Required information | Example |
|---|---|
| Application | Packaging conveyor |
| Motor supply | Three phase, stated voltage and frequency |
| Input | Motor kW and rated rpm |
| Output | Required rpm, continuous and peak Nm |
| Duty | Hours/day, starts/hour and load type |
| Installation | Mounting position, shaft, flange and available space |
| Environment | Ambient temperature, dust, water and corrosion |
| Commercial data | Quantity, destination and required documentation |
Compare SMK worm gear motors and request a matched model, review NMRV worm gearbox specifications, or use the detailed ratio and torque calculation guide.
Frequently asked questions
What is a worm gear motor?
It is an integrated electric motor and worm gearbox providing right-angle power transmission, reduced speed and increased torque.
How do I choose the ratio?
Divide motor speed by required output speed, then choose the nearest available ratio and verify exact speed and rated torque from catalog data.
Are worm gear motors self-locking?
Not always. Backdriving depends on design and operating conditions, and assumed self-locking must not replace a safety brake.
What should I send for selection?
Motor supply and power, input and output speed, continuous and peak torque, duty, mounting, shaft or flange dimensions, environment and quantity.