In general terms, a coupling is a joint that connects two devices. Thus, there a many types of couplings and coupling applications. Most often, couplings are used to transfer power, often at an angle or offset, from one shaft to another. A rigid coupling is simple in design and applicable to near in-line applications. Flexible couplings are more intricate in design and applicable to angle and offset applications.

Flex couplings also compensate for vibrations and misaligned machinery. Flexible couplings consist of two hubs with a flexible disk or pin, an embedded spring or floating gear in between. These designs efficiently transfer torque even when machine precision deteriorates, which ultimately prevents breakdown and wear.

Here are a few other types of couplings:

1. A pipe coupling connects two pipes, usually in-line, and either clamps or screws them down tight.

2. Fluid couplings, a type of hydraulic coupling, functions similarly to clutches and are used in boats and cars.

3. Quick disconnect couplings, or quick couplings, are useful in industrial pneumatic machinery where speed changes are of the essence (often to avoid fluid losses).

4. Electrical couplings are useful for electrical power transfer applications.

Action Steps
The best contacts and resources to help you get it done

Play it safe: Install quality couplings

Couplings take a lot of the stress off other moving parts; but by doing so, they are prone to wear and breakage. Under pressure, even a stationary pipe coupling can release one of the pipes it holds. Coupling failure creates production slowdown, machine damage and potential hazards for the people who work around machinery. Besides smart and safe overall machine design, installing couplings of adequate quality is safe and money-wise. When choosing a coupling don't limit your search to dimension and fit. Temperature, pressure and vibration levels, load and torque capabilities and corrosion resistance are all important factors. Estimate the harshest conditions your application might put on a coupling, then select one that exceeds those values.

I recommend: For an example of what you'll be looking for, scroll down Omega Engineering's page on high temperature brass couplings.

Shop the best sources for couplings

With so many kinds of couplings, you'll need to find the right source to fit your needs.

I recommend: As usual, Grainger comes closest to having it all. Climax Metal Products Company specializes in-collar and rigid couplings. Shop Straub for a pipe coupling. Mesa Systems Company is an excellent source for electrical couplings. The Precision Alliance isn't the right source for all flexible couplings, but it provides high-quality parts. If you need a quick coupling, check out the TradeKey directory.

Maintain your couplings

Many couplings are designed with a definite lifespan. Other, high quality, couplings are made to last indefinitely. Some couplings even have seals over their moving parts to prevent corrosion and keep out dirt. However, even quality couplings require maintenance or even part replacement.

I recommend: Pay attention to manufacturer information. Direct Industry, for instance, provides information on their website and sends instructions along with every jaw coupling shipment. Also, take a look at the troubleshooting guide at Richards Co.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Flexible couplings are useful to insulate one electrical component from another.
• •  Brass couplings contain copper; when they are connected to galvanized steel, corrosion will occur.