Types of gear reducers: coaxial, parallel-shaft, bevel-helical and worm
Gear reducers differ by shaft arrangement and gear type. Understanding the four main architectures is the first step to choosing well.
Coaxial (in-line)
Input and output shafts are aligned. They use helical cylindrical gears: high efficiency (typically 95–98% per stage) and a compact axial footprint. Ideal for conveyors, positive-displacement pumps and general machinery. At Rossi this is the E/ES series.
Parallel-shaft
Output shaft parallel but offset from the input, often with a hollow shaft for direct shaft-mounting on the driven axle. High efficiency and high torque, compact in height. Suited to mixers, heavy conveyors and hoisting. H series.
Bevel-helical (right-angle)
Shafts cross at 90° thanks to an input bevel set, then helical gears. Good efficiency (94–97%) and very high torque with a right-angle layout. H series in the bevel-helical version.
Worm
Non-intersecting right-angle shafts: compact and economical, quiet, with high ratios in a single stage. The downside is lower efficiency (from ~90% at low ratios down to 45–60% at high ratios), with possible self-locking at high ratios. A series.
How to choose
- Maximum efficiency, in-line shafts? → coaxial (E/ES)
- High torque, shaft-mounting? → parallel-shaft (H)
- 90° output, high torque? → bevel-helical (H)
- High ratios, tight budget, 90° output? → worm (A)
Compare the architectures in the Rossi catalogue or start from torque and speed in the selector. See also our guide to the service factor.
Häufige Fragen
Which gear reducer has the highest efficiency?
Coaxial and parallel-shaft reducers with helical gears reach 95–98% per stage. The worm has the lowest efficiency, which falls as the ratio rises.
When is a worm gear reducer the right choice?
When you need high ratios in a single stage, a 90° output, quiet running and low cost, and efficiency is not critical. At high ratios it can become self-locking.