What Mechanical Couplings? Types of mechanical couplings and their uses

Mechanical coupling plays a pivotal role in the connection of two shafts belonging to distinct machinery, such as the motor and wheel shafts. Essentially, it facilitates the linkage between the driving and driven shafts. There are scenarios where a shaft exceeding 7 or 8 meters is necessary. In such instances, coupling two shafts together enables us to attain the desired length while mitigating the impact of shocks. The primary objective of coupling is to unite dissimilar shafts, yet it’s crucial to acknowledge that diverse coupling types are essential due to varying conditions. Today, we will delve into the exploration of different varieties of couplings.

The Importance of Coupling:

– Connecting two different machines.

– Transmitting power from the drive shaft to the driven shaft.

– Reducing the impact of shocks on the equipment.

– Eliminating overload problems in equipment.

Types of Mechanical Coupling:

This is the simplest type of coupling, comprising a hollow cylindrical part called a muff or sleeve. The muff’s diameter is manufactured to match the shaft’s diameter. The driver and driven shafts are fitted on either side of the sleeve, secured in place by threaded holes and bolts to prevent longitudinal motion. A key and keyway arrangement ensures a slip-free connection between the muff and the shaft. This type of coupling is suitable for transmitting low to medium torque. All components must be adequately strong for proper functioning.


– Cost-effective compared to other couplings.

– Simple construction.

– Consists of only two parts: the sleeve and key.

– Disadvantages:

Unsuitable for misaligned shafts.

– Difficult to assemble and dismantle.

– Limited ability to absorb shocks and vibrations due to its rigid design.

Split-Muff Coupling:


In this type of coupling, the muff or sleeve is not a single piece but rather made up of two semi-cylindrical parts constructed from cast iron. One part is fitted from above the shaft, while the other is fitted from below. These two parts are joined together using bolts or studs, with two, four, or six holes provided to secure the muff.


– The main advantage is the ability to assemble and dismantle without changing the shaft position.

 Flanged Coupling:


In flanged couplings, two flanges are brought together and fitted. Both flanges feature the same number of threaded holes, which are used to fasten them using nuts and bolts. A gasket is employed to prevent leakage. Flanged couplings find widespread use and are suitable for medium to heavy-duty applications. To ensure a secure connection with no slippage, a tapered key is utilized.

Flexible Coupling:


Similar to flanged couplings, flexible couplings incorporate rubber bushings along with nuts and bolts. The rubber bushing, designed with appropriately sized holes, provides enhanced strength to absorb shocks and vibrations more effectively than flanged couplings. Additionally, it accommodates slight misalignments between the shafts.

Oldham Coupling:


Oldham couplings consist of two flanges connected by a middle plate. The key advantage of Oldham couplings is their ability to accommodate high parallel misalignment.

Universal Coupling:


Although the angle may remain constant, it can change during operation. The primary application of universal couplings is in heavy vehicles

Gear Coupling:


Gear coupling is a specific type of coupling that falls under the category of flange couplings. It differs from standard flange couplings as it comprises separate parts, namely the flange and the hub. It finds application in heavy-duty scenarios where robustness is essential.Gear couplings are particularly suitable when there is an angular displacement of 4 to 5 degrees in the shafts. Generally, they have a 1:1 gear ratio between the internal and external gears.

Fluid Coupling:


Fluid coupling involves connecting one shaft to the power supply and the other to the power generator shaft. It consists of a pump connected to one shaft and a turbine connected to the second shaft. Over time, the speed of the pump impeller and the turbine equalize, resulting in power transmission.

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