• Home

January 30, 2023


Gear couplings refer to the three piece shaft couplings used for connecting driven and driving shafts of mechanical power transmission assemblies. They help in countering the inevitable misalignment occurring between the two connected shafts.

Gear Coupling Design:

Gear couplings comprise of identical right and left external toothed elements connected with an internal tooth sleeve consisting of matching number of teeth. Most of the times the elements are made of steel, though nylon is also used in some cases for making the sleeve. Different gear couplings follow different designs. Some use split sleeve and a flanged design bolted during installation. In order to transmit more power between the flanges or transfer friction between adjoining faces of the flange, special coupling bolts are used. The bolt heads are either exposed or shrouded along with a coupling guard.

For the correct functioning of the gear coupling, there needs to be some clearance maintained between external tooth element faces. To avoid premature failure of the coupling due to deprivation of oil, they need lubrication at regular intervals along with shaft seals to keep the same in place. In addition, special grease is needed for preventing oil and soap due to centrifugal effect. One of the main advantages of gear couplings over other designs is their tolerance for axial growth. Another important attribute of these is the distance between shaft ends of driving and driven equipment.

Specifications and Attributes

Following are the important attributes and specifications of the gear couplings:

  • Bore diameter: The bore sizes may or may not be identical on both sides depending upon the model. This size is measured by the diameter of the coupling bore accepting the connecting shaft.
  • Coupling diameter: This refers to the overall coupling diameter.
  • Length: The length of the coupling is measured from end to end of the two end faces of the coupling.
  • Allowed speed: The refers to the maximum rpm the coupling can attain.
  • Maximum rated torque: this is the peak torque rating given to a coupling.
  • Service factor: This refers to a multiplier used for accounting the harsh duty such as frequent starts or stops, high peak loads etc. The calculated torque times service factor should be less than the maximum rated torque.
  • Gap: This is the minimum space between the coupled shafts that must be maintained/
  • Lateral offset: This refers to the maximum tolerable shaft misalignment distance along with the axial dimension accommodated by the coupling. It is also known by the name of parallel misalignment.
  • Angular offset: This refers to maximum angular deviation of the shaft misalignment that can be accommodated along radial dimension. It is also known as angular misalignment.
  • Axial offset: This refers to the maximum axial deviation that can be accommodated along the shaft axes.
  • Shaft coupling fastening: This is the method through which the coupling gets attached to the driven or driving shaft.


In this article, we have discussed the design, attributes and specifications of the gear couplings just briefly. For more information regarding customized options available, it is best to contact your nearest gear coupling manufacturers