Applied Motion Products announces their new PG series of inexpensive planetary gears. Custom designed for use with their new line of brushless DC motors, their first model is available in 42 mm diameter with as many as three gear stages and a wide variety of reduction ratios ranging from 3.65:1 to 393:1. See the website for stocked standard ratios. Output torques ratings range from 3.0 to 15 N-m (425 to 2100 oz-in).

Planetary gearboxes operate as their name implies: A motor-driven wheel transmits movement to three circumferential planet gears running in an internally toothed outer ring which forms one stage. They are arranged on the bearing pins of a planet carrier. The last planet carrier in each sequence is rigidly linked to the output shaft ensuring power transmission to the output shaft. Planetary gear design offers higher speed, load and efficiency combined with low backlash in a compact package when compared with spur gears.

Input and output are co-axial and the shafts turn in the same direction. Their new gearheads are suitable for clockwise and counter clockwise rotation, for alternating, continuous and cyclic operation. Unlike other gear types, their compact design provides ultimate power density and excellent torque transfer in the smallest space. Their resistance to shock loads is high due to load distribution over several components (the three planetary wheels) and the support of the annular gear. Their planetary gears come in non-integer ratios – for example our 5:1 nominal ratio is in fact 5.18:1. The reason for this is to evenly distribute gear wear among all teeth and avoid the case where same gear teeth mesh every rotation.