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What is a Disc Coupling?

M. McGee
M. McGee

Disc coupling is a method of transferring power between two shafts. Couplers connect to the ends of the two shafts, creating a bridge between them. Couplers usually have a small amount of leeway in their design; this accounts for shaft mismatching and gives a small amount of flux during operation. There are two primary types of disc coupling systems; single disc and double disc. These disc coupling systems operate in a similar manner, but the double-disc system has more freedom than the single-disc version.

One of the basic functions in every power generation system is turning shafts. Whether power comes from an outside source, such as a water wheel, or from inside the system, like a car engine, nearly every power system relies on a shaft. This turning provides the basic power that is moved through the system to operative areas.


One of the more difficult parts of any power system is transferring the power into the necessary areas. If the shaft is too rigid, it will break or bind under stress; but, if it is too loose, it will lose power. In order to combat this problem, users came up with a system called coupling. Coupling takes two shafts and connects them together using an external connection. When coupled, the two shafts turn as one, but do not touch.

Generally, once coupled, the two shafts are permanently joined. Most coupling systems create a semi-permanent connection; it only comes off if a piece physically breaks. This connection allows power and torque to transfer between the shafts with very little loss of power.

Coupling provides other benefits as well. When the shafts are coupled, variances in the shafts’ positions may be accounted for. This allows two shafts that don’t line up perfectly to still transfer power as though they did. In addition, coupling allows the shafts to bend individually. When put under high stress, the two shafts flex independently of one another, increasing the tension that may be applied to the system before a shaft breaks.

A disc coupling system is a low-profile and adaptable type of coupler. A single disc coupling system is comprised of two hubs that connect to the two shafts and a disc spring that connects them together. These couplers flex much more than other coupling systems, since they have a connective spring rather than a fixed connection.

The double-disc version is nearly the same as the single, except it has a secondary disc in between the two hubs. Each hub is connected to a spring, and those two springs connect to the center disc. This center disc creates an even greater flex point, as there are two springs rather than just one. In addition, the center disc may be made of an insulating material, preventing the transferal of heat and electricity across the connection.

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