Elastomeric Flexible Couplings

Tire Couplings

Tire-type couplings are similar to car tires. These couplings consist of two flanged hubs fitted with clamping plates that clamp the hollow annular member of the coupling at their inside edges. Tire coupling elements are rubber or polyurethane derivative elastomers with layers of cord, such as nylon, vulcanized into the tire shape. The clutch transmits torque through clamping friction applied to the inner rims of the tire and element shear. 

If the clutch fails, usually only the elastomer part is replaced. Axial forces on the shaft, caused by centrifugal forces acting on the elastomer, limit the speed of these couplings. In addition, their bulky size limits the applications they can be used in, although an inverted tire variant exists to reduce the size of the hitch. 

Jaw Couplings

The jaw coupling or spider clutch is a universal industrial power transmission device. The jaw clutch is a flexing material clutch that transmits torque through the compression of a resilient spider insert placed between two intermeshing jaws. These couplings have two protruding jaw hubs that mate with a one-piece elastomeric spider insert. For higher power applications, the spider can be replaced with individual load bearings. Torsional stiffness and torque capacity vary with the number, width and shape of the jaws. 

They operate over a temperature range, handle angular misalignment and associated reactive loads, are chemically resistant, and have good speed and damping characteristics. They are not very tolerant of misalignment compared to other flexible coupling types. The design of the dog clutch is considered a failsafe, which can be a positive or negative factor depending on the application.

Pin And Bushing Couplings

They are simple types of flexible couplings with two flanges bolted to the support bolt and a nut covered by a rubber bushing. Pin-socket couplings consist of two hubs, which can be made of different materials, with pins at the contact points of the rubber bushings. Relative movement is accommodated by compression of steel bonded bushings. This type of coupling tolerates a lateral offset of 0.5 mm and 1. Angular offset of 5°. 

These couplings are primarily used as flexible links in applications where reliable link transmission is required under severe operating conditions. Due to their simple structure, these are cheaper. They are often used for lifting applications. 

Torsional couplings 

Torsional couplings are primarily used to absorb torsional vibrations. Most of these are rubber couplings that can dampen vibrations transmitted from one shaft to another and also accommodate misalignment. Spring torsion clutches are available as torsion clutches. 

The purpose of a torsional clutch is to tune the system above or below its natural frequencies. Both torsionally soft (with soft rubber) and torsionally stiff (often with hard plastic) are available to adapt to the system. These are very stiff clutches designed to shift critical speeds well above the operating range.