Gearmotors 101: Types, Uses, and Benefits — Technical Summary for Engineers

A gearmotor is a system essential when effectively moving any motor-powered machines. Considering its significance in terms of adjusting the mechanism’s speed, it’s crucial for engineers to know what a gearmotor actually is, the many types and uses it has, and why gearmotors are so beneficial.

What Is a Gearmotor?

Basically, a gearmotor is an electric motor equipped with a geartrain. Gearmotors use either Alternating Current (AC) or Direct Current (DC) power.

In the majority of cases, the inclusion of a gearbox is designed to limit the motor shaft’s speed, and enhance the motor’s capacity to output torque. You can learn more about motor torque here, but simply put, torque in motor vehicles means how fast the vehicle accelerates. It also indicates how easily the vehicle comes into motion from rest. So, the higher the torque, the higher the acceleration capacity in minimum time.

Gears transform shaft speed directly into torque at precise ratios, with little to no efficiency losses. This makes it easier to set up the right torque output and speed via adding the accurately sized and configured gearbox.

Gearmotors: Different Types and Uses

Two most common types of gearmotor are inline gearmotors and right-angle gearmotors:

  • Inline gearmotors use planetary gear sets or spur gears.
  • Right-angle gearmotors typically use bevel, worm, or hypoid gearing.

Gear motors can be bought with a variety of AC or DC motor types. They also come in a number of reduction ratios to accommodate many applications like robotics, food and beverage equipment, automatic door operators, etc.

Spur Gearmotors

Spur gearmotors transfer power through parallel shafts. Their teeth are identical to the shaft axis, which causes the gears to generate radial reaction loads, not on axial loads, but the shaft.

Spur gearmotors are noisier compared to helical gears as they operate amidst a single line of contact between the teeth. As the teeth continue rolling through the mesh, they meticulously roll-off contact with one tooth and then accelerate to contact with the next. This is very different than a helical gear, which has multiple teeth in contact and transmits torque more efficiently and smoothly.

Helical Gearmotors

Unlike a spur gearmotor, helical gearmotors have teeth oriented at a certain angle to the shaft. This causes multiple teeth to come in contact during the operation. As opposed to spur gearmotors, a helical gear is able to carry more load.

Because of the load-sharing between the teeth, this particular arrangement allows a helical gearmotor to run smoother and even quieter than most other gearmotors. They produce a thrust-load during runtime, which should be highly considered when used. Helical gearmotors are commonly used in enclosed gear drives.

Double Helical Gearmotors

A variation of the helical gearmotor, double-helical gearmotors have two helical faces placed alongside each other, and a gap that separates them.

Both the faces have identical, yet different helix angles. Boasting a double-helical set of gearmotors reduces thrust-load and enables even better tooth overlap with smoother operation.

Herringbone Gearmotors

Although similar to double-helical gearmotors, herringbone gearmotors don’t have any gap dividing the helical faces. They are usually smaller than double-helical gearmotors and are best suited for high shock/vibration applications.

Herringbone gearmotors aren’t widely used because of their manufacturing costs and difficulties.

Bevel Gearmotors

A bevel gearmotor is commonly used when transmitting power between the shafts intersecting at a 90-degree angle. These are used in various applications where right-angle gear drives are needed.

A bevel gear tends to cost higher and cannot transmit torque like the parallel shaft arrangement.

Worm Gearmotors

This particular gearmotor transmits power through the right angles on nonintersecting shafts. Worm gearmotors produce a decent thrust-load and are suitable for high-shock load applications. However, they offer low efficiency than other gearmotors. Therefore, worm gearmotors can often be seen in a lower horsepower application.

Hypoid Gearmotors

Spiral bevel gearmotor and hypoid gearmotor have similar looks, but the latter operates on shafts that don’t intersect. In this arrangement, as the idea is set on a diverse plane than the gear, a set of bearings is supporting the shafts (on either end).

Gearmotor Benefits:

  • Using the right-sized gearhead and motor combination for an application prolongs the gearmotor’s life and enables maximum power management and utilization.
  • Quieter operation owing to integral castings and pinions that are hobbed or ground on the armature/rotor shaft. Also, fewer parts requiring arrangement results in a near-perfect alignment of the pinion, rotor, and geartrain.
  • Little to no risk of lubricant leakage, thanks to the “O-ring” and lip-seal construction. Designs are more compact and lubrication is better controlled.
  • Gearmotors reduce the need for gearhead/motor couplings and discard any possible bearing alignment issues, common when a gearhead and motor are bolted together by the end-user.

Wrapping Up

If you made it this far, it’s safe to say that you’re all caught up with gearmotors and how they operate. Once you’ve chosen a gearmotor, make sure to run a few tests to check if it runs well in a certain operating environment. Taking the time to prepare will let your gearmotor last longer and operate at peak performance.