Types of Gearboxes

Author: Robin Olson

Category: Gear

Article Tags:

concentric

concentric gear drive

gear box

gear drive

parallel

parallel gear drive

right angle

right angle gear drive

shaft arrangement

types of gear drives

types of gearboxes

Gearboxes, also known as gear drives, are named for either the arrangement of their shafts or the way that they mount to the driven equipment. However, it is important to realize that shaft arrangement and mounting are two different characteristics of the drive. Therefore, it is important to know both aspects to successfully determine the best gearbox for your application.

What is Gearbox Shaft Arrangement?

The shaft arrangement on a gear drive is the location of the high speed and low speed shaft extensions relative to each other. This is dictated by the position of the motor and driven equipment and sometimes constrained by the physical space of the application.

The orientation of high and low speed shafts as they relate to the naming of the different types of gear drives may seem very simple, but there are reasons why you would choose one over the others when determining the best gear box for your application. The primary determinant for selecting the type of gearbox is space limitations in a system. Because the shafts are oriented differently, your driving equipment, or motor, will be in a different location depending on which type of gear drive is selected.

Learn the Different Types of Gear Drives

In general, there are three different types of gearboxes: concentric, parallel, and right angle. A fourth type called shaft mount is also used in situations where the applications are in a configuration where they cannot be mounted by foot. We will discuss mounting positions in greater detail later in this post.

Review the chart below for an overview of each drive, then read on to learn more details about each drive and the industries and applications that use them.

Type of Gearbox	Shaft Arrangement	Mounting
Concentric	High and low-speed shafts are on the same horizontal and vertical plane	Foot mounted
Parallel	High and low-speed shafts are on the same horizontal plane and parallel to each other	Foot mounted
Right Angle	High and low speed shaft have a 90-degree relationship	Foot mounted
Shaft Mount	The gearbox is mounted directly onto and supported by the driven shaft	Shaft mounted

Concentric Gearbox

A concentric gearbox, also referred to as an inline gear drive, is one in which the high and low speed shafts are on the same horizontal and vertical planes. These units allow several units to be placed in a row because of the straight-line alignment of their shafts. A planetary gearbox is a type of concentric inline gear drive that is typically used in applications requiring higher torque due to its rugged design.

View Rexnord’s line of concentric gear drives.

Parallel Gearbox

A parallel gear drive is one in which the high and low speed shaft are on the same horizontal plane and parallel to each other. Parallel shaft gear boxes are usually selected for high torque and high horsepower applications.

View Rexnord’s parallel gearbox products.

Right Angle Gearbox

A right angle gear drive is one in which the high speed and low speed shaft have a 90 degree, or right angle, relationship. These drives are often used on conveyors or other applications that require the driving equipment to be close to the driven equipment. The 90-degree orientation also makes right angle gear drives ideal when using a large drive that is mounted directly to the shaft to minimize shaft bending loads.

The right angle vertical drive is a right angle gear drive with the low speed shaft oriented in the vertical direction. It is typically used in mixing or crushing applications, with the gear drive mounted above or below the equipment.

View Rexnord’s line of right angle gearboxes.

Gearbox Mounting

There are two ways to mount a gearbox into a system: foot-mounted or shaft-mounted. Like shaft arrangement, mounting is determined by the space and structure limitations in the system. Foot-mounted gear drives are mounted to a foundation or baseplate through bolt holes in their feet. That may seem simple, but it requires the foundation to be sufficiently rigid to support the drive and the torque passing through it. These drives are sensitive to soft-foot, a condition that occurs when the feet are not level to each other which causes misalignments between the shafts. Foot mounted drives should also be on foundations that are well connected to the motor and driven equipment foundations. This prevents the equipment from moving independent of each other, which also causes misalignment and vibration.

If it is not possible to place a foundation for the motor, gear drive, and driven equipment into the application, the gear drive may be shaft-mounted to the application. In this case, the gear drive low speed shaft is rigidly connected to the driven equipment shaft. This can be done by making the low-speed shaft of the gear drive hollow and securing it in place around the solid shaft of the drive equipment with a bushing and keeper plate. It can also be done with a rigid flange coupling that connects the sold shafts of the gear drive and driven equipment together.

When a gear drive is shaft-mounted, it hangs in space by the low-speed shaft connection. The motor can be direct coupled to the gear drive via an adapter, a scoop mount, or a swing base. It can also be mounted on top of or next to the reducer via belts or chains. The gear drive and motor system will want to rotate about the gear drive’s low speed shaft, so a torque arm is required to bolt into some structure and prevent rotation.

Over time, the term “shaft mount” has become nearly synonymous with relatively small gear drives that are designed without feet for light conveying applications.

Learn about Rexnord’s Quadrive shaft mounted gearbox.

Industries, Applications, and Products by Type of Gearbox

	Industries	Applications	Rexnord Product
Concentric	Agriculture Automotive Cement Energy Forest Mining	Heavy duty bulk material handling Heavy duty process specific Water treatment Aggregate & construction equipment Grain handling	Planetgear UltraMax Ultramite UC
Parallel	Agriculture Automotive Cement & Aggregate Energy Mining Pulp & Paper	Conveying Reclaimers/stackers Crushers Mills Feeders Pumps Dryers Mixers/blenders Agitators Loaders/unloaders Elevators	A+Plus Falk V-Class Y-Unit
Right Angle	Automotive Food & Beverage Cement Forest Mining	Conveying Reclaimers/stackers Crushers Mills Feeders Pumps Dryers Mixers/blenders Agitators Loaders/unloaders Elevators	A+Plus Falk CT-Series Falk V-Class Omnibox Ultramite UB Ultramite UW
Shaft Mount	Cement & Aggregate Sand-Gravel Mining Grain Baggage/Package Handling Pic-Pac-Retrieval Energy Metal Processing	Light to medium duty conveying Belt conveyors Classifiers Separators	Quadrive Planetgear SMP

When selecting and sizing a gear drive, keep in mind that the orientation of the shafts and the type of mounting must both be used to fully specify the gear drive. Learn more about our full line of gear products.

Robin Olson

Robin is the Director of Applications Engineering at Rexnord Industries, Gear Group. In 1995, Robin joined Falk, which was acquired by Rexnord in 2005, and has previously worked in the Engineering Technical Services, Warranty, Product Engineering, and Marine Product groups during her career. She is active in the American Gear Manufacturers Association (AGMA), acting as a contributing member of the Helical Gear Rating Committee, Chairperson of the AGMA 925 (Gear Surface Distress) subcommittee, and is honored to act as US delegate to ISO Working Groups 6 (Gear calculations) and 15 (Micropitting). Robin holds a Bachelor of Science in Physics from the University of Wisconsin - LaCrosse and a Master of Science in Physics from the University of Wisconsin - Madison.