What is Shaft Coupling?
Couplings are mechanical elements that connect two drive elements, allowing the motion from one to the other. Shafts are commonly used as drive components. So, a shaft coupling is a mechanical feature that connects two shafts to transfer torque from one end to the other while accepting misalignment.
Shaft couplings add mechanical stability, allowing for shaft misalignment tolerability. As a result of this coupling stability, irregular bearing wear, machinery vibration, and other mechanical issues caused by misalignment may be reduced. As a consequence of this coupling stability, irregular bearing wear, machinery vibration, and other mechanical problems caused by misalignment may be reduced.
Even where the motor and workpiece are closely attached and properly secured, minor misalignments may occur over time due to temperature fluctuations and changes in time, resulting in vibration and damage.
Shaft couplings play an important role in reducing shock and vibration and allowing for smooth rotation. In a broader sense, shaft coupling may also refer to a mechanical system that connects neighboring sections or ends of objects.
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Types of Shaft Couplings
There are several types of shaft couplings available depending on the application such as: Beam, Bellows, Chain, Jaw, Diaphragm, Disc, Grid, Oldham, Schmidt, and Clamping. Let’s read more about them:
Beam Couplings
This coupling is one of the types of shaft couplings. The beam coupling is made up of a single or several helical cuts in the coupling body and can accept parallel misalignments of up to 0.025 inches and angular misalignments of up to 7 degrees.
They are mainly used in motion control applications for torques of less than 100 inch-lbs. There are zero-backlash designs available to ensure precise positioning of the driving and guiding shafts.
Bellows Couplings
Bellows couplings are also appropriate for motion control applications. They are made up of multiple metal convolutions that provide high torsional stiffness, which is critical in positioning applications.
Torsional stiffness limits the amount of angular and parallel misalignment they can tolerate as compared to beam couplings, though torque transmitting capacities are roughly comparable.
Chain Couplings
Chain couplings are designed for power transmission applications and can transfer power up to hundreds of horsepower. Misalignment allowances for angular and parallel misalignment are usually 2 degrees and 0.015 inches, respectively. Typical chain couplings employ special chain sprockets and double large roller chains, the clearances of which enable the design to function as a flexible coupling.
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Jaw Couplings
Next to the above types of shaft couplings, Jaw couplings are another type. Curved and straight jaw couplings, which are made up of pairs of multi-jawed hubs that mate with elastomeric spiders, are used for both motion modulation and light power transfer applications. Backlash-free torque transfer is possible thanks to the specification. Accommodation for parallel misalignment is usually less than 0.01 inches, and angular misalignment is less than 1 degree.
Elastomeric spiders have damping power to these couplings, and the spiders are often available in various durometers to lend particular properties to the individual couplings. These couplings often work without lubrication and can convey torques of up to 1000-inch pounds.
Diaphragm Couplings
Diaphragm couplings are often used in high-power transmission applications such as turbomachinery. They usually use one or more flexible metal convoluted disks to transfer power to an inner spacer shaft and then back out to the powered machinery by another diaphragm stack. The lack of lubrication criteria is a significant improvement over gear form couplings. Diaphragm couplings can transmit high torque and operate at high speeds.
Disc Couplings
There more are types of shaft couplings. Disc couplings have one or more disks and one or two steps that bolt to the shaft hubs. They are power transmission devices that rely on the stability of their thin metal disks to transfer torque and tolerate angular misalignment.
They are not very adept at dealing with parallel misalignment. They can transfer high torques and are often used to pair high horsepower engines, gas turbines, and so on to loads.
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