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October 31, 2022

Gear Couplings: Design and Attributes

Gear couplings are the flexible three piece shaft couplings that are used for connecting driving and driven shafts in the mechanical power transmission industries. They are mainly used to counter the misalignment occurring between the connected shafts. Let us know more about them.


The basic design of gear couplings consist of identical left and right hand tooth elements connected with the help of an internal toothed sleeve with a matching number of teeth. Generally, gear coupling manufacturers make them from steel. However, nylon is also used in some cases for sleeve portion. There are some designs that use a flanged split sleeve design that is bolted together at the time of installation. There are special coupling bolts that are used for transmission of power between flanges. Sometimes, they are also used to effect a friction transfer between two adjoining flange faces.

In order to ensure optimum working of gear couplings, they need to regularly lubricated with grease or oil. In order to keep the lubricant in place, shaft seals are used. There is a special coupling grease used by gear coupling manufacturers used to prevent separation of oil and soap due to the centrifugal effect. There are some high speed couplings too that employ flooded oil lubrication to deal with this phenomenon. It is normal for gear couplings to face wear and tear. However, if managed properly with the right lubrication, the life of the couplings can be increased considerably. One of the main advantages of gear couplings over other designs is that they are able to tolerate the axial growth. Another main component of the gear coupling design is the distance between the shaft ends which specify the distance between the driving and the driven shaft faces of the equipment.

Applications of the gear couplings

Gear couplings are mainly used in large industrial machines like blowers, pumps, compressors, mixers and several others. They may also be used in small motion control systems which are equipped with a polymer sleeve. This helps in reducing the backlash. However, there are several other zero backlash designs available with gear coupling manufacturers that are better suited for such applications. This backlash is necessary in case of metal gear couplings as it helps in providing misalignment compensation while also providing clearance for the lubrication to flow between the meshing teeth. Those couplings that come in standard size, are used for serious torque transfer and other high speed operations of the company. They are used in power transmission applications where the motor may be larger than the regular 200 HP in which it is common to use journal bearings.

In order to get a specific gear coupling, one needs to have a complete knowledge of required bore, calculation of the transmitted torque and then applying the multiplier to rate the severity of the machine service. One can consult a gear coupling manufacturers for the multiplier as most of them have an online calculator that helps in providing specifiers for coupling selection.