Gimbals and linkages are examples of limited movement assemblies comprised of components that pivot relative to each other. They present a unique challenge when designing the pivot mechanism.

Gimbal with rolling element bearings (arrow).Gimbal with rolling element bearings (arrow).To align and join these components in a fashion that allows controlled motion relative to one another, the design engineer could use a pin or shaft. However, if the assembly moves with regularity, wear and friction will become a problem without a bearing. To resolve this issue, plain or rolling element bearings could be used to provide rotary motion. A shaft or pin through the bearing would keep the assemblies aligned and provide the pivoting motion, but threads and nuts or grooves and retaining clips would be required for the shaft to maintain the axial location.

Introducing bearings and other components add to the complexity, expense and assembly time.

What if there was an easier solution?

Flexure bearings, also referred to as pivot bearings, were designed precisely to tackle the design challenge of limited movement rotational assemblies. They are constructed of stainless steel, non-contacting sleeves

Single-ended pivot bearing. Source: C-Flex Bearing Co., Inc.Single-ended pivot bearing. Source: C-Flex Bearing Co., Inc.

connected internally by leaf springs. This allows the sleeves to rotate relative to one another without touching or creating any friction. Flexure bearings are extremely repeatable with low hysteresis characteristics and high radial and axial stiffness. As they do not wear and do not require lubrication, they are also maintenance-free.

A single flexure bearing can take the place of bearings, shafts or pins and retaining components, simplifying the design as well as reducing the component cost and assembly time.

Cantilever, or single-ended, flexure bearings have two sleeves. One half of the bearing is fixed, while the other is mounted in the pivoting component, allowing limited rotation. Double-ended bearings have three sleeves and are designed for central mounting with two pivotal arms.

Although flexure bearings are recommended for radial loading applications, they can also be used for axial, moment or torsional loading applications. When used in radial load applications, the bearing orientation determines whether the springs are placed under tension or compression.

Gimbal with flexure bearings. Source: C-Flex Bearing Co., Inc.Gimbal with flexure bearings. Source: C-Flex Bearing Co., Inc.

Among the variables that can be specified:

  • Size
  • Special materials
  • Clamping options
  • Maximum deflection angles (typically +/- 30°)
  • Sleeve geometry

For additional information see:

C-Flex Bearing Co., Inc. Supplier Profile | Design Guide

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