A coupling is a device used to connect two shafts in a machine. Couplings transfer movement and power. They are either rigid or flexible. Different types of couplings have different features and can differ greatly in design. Some couplings connect to shafts without moving them. Others, however, require shaft movement. Read on to learn more about couplings and what you should look for in a coupling. And, remember to check the coupling specifications before purchasing a coupling.

Fluid couplings, also called hydraulic couplings, transfer power through a transmission fluid. They are used in heavy industry for many applications that require rotational power, such as industrial gearing and conveyor belts. Fluid couplings are also beneficial for preventing damage to machinery. Unlike mechanical clutches, fluid couplings allow for safe, smooth start-ups without jarring the engine. And, unlike mechanical clutches, they can be used for both high-inertia starts and continuous cyclic loading.

Fluid couplings use an impeller to accelerate a fluid, which is then transferred to the rotor. Fluid couplings have different stall speeds, and a fluid-powered coupling can only turn at a certain speed when locked. This means that the coupling can’t reach its full power efficiency because the angular velocities are similar. Unlike mechanical clutches, fluid couplings can only achieve their full power efficiency under extremely high loads.

In addition to transferring power, couplings also accommodate misalignment, compensate for axial movement, and absorb shock. The type of coupling required depends on four basic shaft conditions. The first condition is known as parallel misalignment, and it refers to a situation where two shafts are not coaxial. This type of misalignment may be symmetrical or asymmetrical. Regardless of the case, couplings are used to join two shafts together.

Proper alignment is critical for couplings. Often, couplings are selected too late in the application design process. They must meet several criteria, including torque, misalignment, stiffness, inertia, and RPM. In addition to these, environmental conditions, service factors, and cost must all be considered. Only a coupling that meets these criteria can work properly. A poorly chosen coupling can cause a significant inconvenience and, in some cases, lead to personal injury.

While lubrication is essential for couplings, you should also pay special attention to contamination control. Any particulate contamination can cause abrasive wear and tear on the three bodies. And, too much cycling of the coupling may cause the coupling to overheat. So, make sure to choose the proper lubricant for your application. A minimum operating temperature of -10deg F is required. If the coupling is over-cycled, a 7% slip may cause overheating.

The right amount of fluid is crucial for proper operation of a coupling. If you don’t use enough oil, the coupling will not function properly or may even break down prematurely. Likewise, too much oil can cause a hard start, and too little oil can damage the coupling. Therefore, the right amount of oil should always be used. If it is too thin, the coupling may not function properly. If you use too little oil, the friction will be reduced and could lead to a hard start.