If gearmotor cost, gearhead noise, and overall gearmotor length are critical factors, we find that design engineers often drop the requirement for a planetary gearhead and instead select a more compact right-angle or inline (helical) gearhead solution. However, there are certain applications where the benefits of a planetary gearhead outweigh its disadvantages. Below is a brief review of advantages and disadvantages of small planetary gearheads used with fractional horsepower small motors (FHP = <746 Watts) .
Advantages of planetary gearheads:
- Compact size and low weight – as much as 50% reduction with same torque output.
- High power density – several planets share the load rather than one gear, the more planets the more sharing.
- Longer gear life at similar loads.
- Gearing can be very accurate with virtually no backlash.
- High efficiency – 95% per stage is common.
- Typical ratio per stage is 9:1, 4 stages 9000:1
- Coaxial arrangement – no offset output shaft
- Modular, most planetary stages can be stacked.
Disadvantages of planetary gearheads:
- Noisier Operation – some planetary gearheads are noisy.
- Gearing must be accurate to assure load sharing
- High bearing loads can lead to early wear in dead stud or sleeve bearing construction
- Generally grease lubricated (oil bath is the better).
- High ratio of length to diameter when using multiple stages (gearhead gets very long).
- High cost if low backlash and long life are required
Custom Gearmotors: Bodine type 22B4FEBL-60P, 24 VDC brushless DC gearmotor (also available with 130 VDC winding). This example shows a 2-stage, 30:1, 76 lb-in, 60 mm diameter gearmotor developed for an OEM application. The gearhead has a continuous duty rating of up to 226 lb-in (26 Nm), with available gear ratios from 4:1 – 162:1. Gearing efficiency varies with the number of gear stages. Minimum annual order quantities apply for custom designs. AC inverter-duty options with our 30R motor are also available for OEM designs.
To view our stock selection of planetary type 24A4-60P PMDC gearmotors, click here. 12, 24 and 90/130VDC models available.
Copyright Bodine Electric Company © 09/2017. All rights reserved.