Video: ElectroCraft LRPX 22 and 32 gearmotors have operating ranges optimized to the subcomponents

In a recent video on new ElectroCraft motors, my colleague Paul Heney and I got to review integrated offerings that let designers get higher torque even while maintaining efficiency. The LRPX units are sold as gear motors — not as motor with added gearboxes. This means motor performance is optimized for gear input limitations. An eight-pole design makes for higher torque density and peak motor efficiency is within gearbox speed range.



The LRPX 22 and 32 integrate low-rpm RPX motors with a custom planetary gearbox for a compact BLDC motor capable of high output torque at low rpm — as well as quiet and smooth operation.

Traditional small-frame BLDC motors deliver peak performance at high rpm — but the catch is that such high rotational speeds are usually too high to make efficient use of a gearbox. In fact, even when a traditional small-frame BLDC motor is paired with a custom high-rpm gearbox, there are typically noise and heat issues that make them unsuitable for critical applications. Why? Well, consider how a traditional coreless BLDC design is based on tooling-intensive winding technology developed for brush motors. Representative offerings here include slotless stators and encapsulated connections and sintered ring magnets — with two poles and no skew. Unfortunately, peak performance for such designs is usually at about 20,000 rpm … yet the gearboxes that usually get paired with such motors require far lower speed — usually of about 6,000 to 8,000 rpm.

In contrast, the BLDC motors in the LRPX family allow for pairing with specially tailored planetary gearboxes. The holistically developed design makes for high torque from a small form factor, with low power consumption and peak performance at low rpm for quiet operation as well.

The LRPX units are sold as gear motors — not as motor with added gearboxes. This means motor performance is optimized for gear input limitations. An eight-pole design makes for higher torque density and peak motor efficiency is within gearbox speed range. More specifically, there’s up to twice the torque within the gearbox’s speed range than with traditional setups.

The LRPX22 we got from ElectroCraft has a 22-mm diameter and delivers peak torque to 3.0 Nm — or 424.8 oz.in. for imperial types. Continuous stall torque is to 2.5 Nm and maximum output rpm is 514. In contrast, the LRPX32 is a 32-mm motor with a peak torque of 8.0 Nm, a continuous stall torque to 6.0 Nm, and speeds to 2,489 rpm.