What is a gear bearing?

A gear bearing is a type of rolling element bearing similar to a planetary gear. A gear bearing consists of a number of smaller “satellite” gears that rotate around the center of the bearing along a track on the outside of the inner and satellite gears and on the inside of the outer gear. Each gear is between two concentric rings. Therefore, the satellite gears must all be the same width.

Gear bearing operation:

Sliding friction of the conjugate profile in motion is minimized. The end rollers limit the radial displacement of the gears at their contact points in order to achieve a sliding-free rolling motion when the gears are engaged.

The adjacent end faces of the teeth and rollers limit the axial displacement of the conjugate bearing gears in plane-parallel motion. In this way, the use of bearing gears as sun wheels, tooth rings and more than two satellite gears uniformly distributed between them constitute the entire gear bearing, which can be used as a bracket instead of tooth rings or sun gears, or as a frame unit and transfer of rotation from the satellites, while the limitation of carrier degrees of freedom creates redundant constraints or serves as an additional basis for force distribution in the mechanism.

Usage of Gear Bearings:

When used as a planetary gear unit with simplified kinematic relationships and/or suspension, gear bearings can be used as more efficient bearings. Double-row planetary gear combinations can also be used. This is especially true for direct analog indication systems, such as measuring instruments and planetary watches.
Linear gear bearings can easily be made into linear tracks. One, cast in bronze, is used as an expansion joint in the center of the Kingsgate bridge.

How to implement gear bearings:

The implementation of gear bearings can be manufactured as a whole or as a fixed joint assembly, using: screws, spacers, threaded connections, pressure coupling, welding, soldering, gluing or friction coupling in the form of a sliding safety clutch or friction connection. Gear bearings can also be assembled from separate segmented parts or by combining them with optional elastic and/or thermal deformation in the manufacturing sequence.

Advantages and disadvantages of gear bearings:

Advantages of geared bearings:

♦ Simple implementation (no bearing cages, brackets, simplified suspensions and mounting systems required).

♦ Increased efficiency due to reduced sliding friction losses.

♦ Fewer satellite gears may be required, as their orbital motion is defined by the gear mesh.

♦ Can be used for direct visualization in measuring instruments.

Gear bearing disadvantages:

May require friction-reducing materials or coatings, as lubricants may be difficult to apply, especially in measuring instruments
High quality standards for manufacturing and assembly