Flexible Shaft Couplings Key Terms

Get acquainted with technical terms associated with flexible shaft coupling products

By Howard Robertson

A flexible shaft coupling is a device used for transmitting mechanical power when the drive and driver shafts have radial, axial or angular misalignment. For selecting the most suitable flexible shaft coupling, you must understand the working of the different types of flexible shaft coupling products available in the market.

If you want to buy a flexible shaft coupling, you will need to understand various technical specifications for your application requirements before communicating with the suppliers of flexible shaft couplings. This guide covers some of the terms related to flexible shaft couplings, such as torque, RPM, shaft alignment and Oldham coupler.

Torque

Torque is defined as the measure of force applied to an object to produce rotational motion. Torque is determined by multiplying the applied force by the distance from the pivot point to the point where the force is applied.
Try: You can read through detailed information about torque at the Department of Physics at University of Guelph.

RPM (Revolutions Per Minute)

Revolutions per minute (RPM) is the number of rotations completed by the shaft in one minute around a fixed axis. It is most commonly used as a measure of rotational speed or angular velocity of mechanical components.
Try: Opto 22, a manufacturer of hardware and software products, provides information about RPM and RPM measurement techniques.

Shaft alignment

Shaft alignment is the positioning of the rotational centers of two or more shafts such that they are co-linear when the machines are under normal operating conditions.
Try: Machine Diagnostics Inc. (PDF), a provider of machine maintenance services, explains the importance of shaft alignment.

Backlash

Backlash (sometimes called lash or play) is the clearance between meshing components. Maintaining optimum backlash is very important, as a larger backlash affects the transmission efficiency of a coupling.
Try: R + W America, a manufacturer of flexible shaft couplings, torque limiting couplings and line shafts, provides information about backlash error.

Torsional stiffness

Torsional stiffness is the measure of resistance of a shaft to the twisting force. Since the purpose of a flexible shaft is to accurately transmit rotary motion with minimum twisting, a high torsional stiffness value is generally desirable.
Try: Huco-Dynatork, a manufacturer of couplings, provides information about torsional stiffness.

Oldham coupler

An Oldham coupler is a flexible shaft coupling product that is useful for connecting parallel shafts. It has three components. The first disc component is connected to the driver shaft, another disc component is connected to the drive shaft and a middle disc component rotates around its axis to transmit power between the two shafts.
Try: To learn about an Oldham coupler, its advantages and disadvantages, read through information available at OEP Couplings, a reputable supplier of shaft coupling products.

Universal joint

A universal joint (also called a Cardan joint) is another shaft coupling product that is useful for connecting parallel shafts where the alignment between the shafts may vary during the rotary motion. These joints are useful for various mechanisms in automotives.
Try: To learn more about universal joints, their types and applications, read through information at GlobalSpec.