10 Questions You Should to Know about Rigid Coupling Supplier

A rigid coupling is a type of shaft coupling used to connect two shafts at their ends to transmit power. In the case of these couplings, the shafts provide a fixed union where torsional flexibility is not required, shaft alignment is maintained, and proper bearing support is provided. To reduce shaft deflection shaft support bearing should be located as close to the coupling as possible. Large couplings and those running at high speed may require balancing to reduce vibration. However, they are simple enough to install.

If you want to learn more, please visit our website CNG.

We classify three categories of Rigid Couplings:

• Flange couplings
• Sleeve couplings
• Ribbed couplings

Flange couplings

Flange couplings are used to connect shafts of the same or different diameters. The device consists of 2 flanged hubs, bored and keyed to fit their respective shafts and joined by bolts. Some have removable bushings for easier replacement. The couplings usually are made of carbon steel and are available to be over 8”  in diameter. The flange-style couplings are primarily designed for heavy-duty applications.

Rigid Flange Coupling by Ringfeder

Sleeve couplings

Sleeve couplings are made from one piece of material; factory bored to accommodate standard shafting. Keyways are broached, and set screws are installed. Shaft keys transmit torque from the shaft to the coupling hubs, and set screws keep the coupling from sliding along the shaft. Sleeve couplings are also made in clamping style. Clamping styles come in two ways: one-piece design and split, two-piece. Split, two-piece couplers can be installed and removed without machine disassembly.

One-piece Sleeve Coupling

Ribbed couplings

Ribbed couplings may be used for heavy-duty services, made of 2 pieces and used to connect shafts of the same diameter. The coupling is keyed to both shafts with bolts. Those permit quick and easy installation and removal.

Ribbed Coupling from TB Woods

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Features of Rigid Couplings

In summary, the benefits of rigid couplings include their low price, high torque capacity, torsional stiffness, and zero backlashes.

In the end, we would like you to watch a short demo video below about flange couplings made by RINGFEDER.

Check our article Gear Couplings: Benefits and Applications.

Feel free to Contact Us if you have any questions, need more information or if you are interested in purchasing a coupling.

HVH Industrial Solutions is an authorized distributor of the following coupling manufacturers: Ringfeder, System Components, TB Wood’s, Ameridrives, Bibby Turboflex, and Guardian Couplings.

We work closely with the engineering teams of the above companies to provide superior customer service and engineering support.

If you are looking for more details, kindly visit Flexible Grooved Coupling.

Most of those fittings are not made in larger sizes so you rigid coupling transition is the only option.

I don't lose sleep over it:

90.4 Enforcement. This Code is intended to be suitable for mandatory application by governmental bodies that exercise legal jurisdiction over electrical installations, including signaling and communications systems, and for use by insurance inspectors. The authority having jurisdiction for enforcement of the Code has the responsibility for making interpretations of the rules, for deciding on the approval of equipment and materials, and for granting the special permission contemplated in a number of the rules.
By special permission, the authority having jurisdiction may waive specific requirements in this Code or permit alternative methods where it is assured that equivalent objectives can be achieved by establishing and maintaining effective safety.
This Code may require new products, constructions, or materials that may not yet be available at the time the Code is adopted. In such event, the authority having jurisdiction may permit the use of the products, constructions, or materials that comply with the most recent previous edition of this Code adopted by the jurisdiction.

This states that the AHJ may waive requirements, and given the lack of available products then the AHJ has ample legal ground to stand on to ignore aspects of 300.15. People always point to 90.4 when it comes to inspectors making up rules in the field, but it doesn't say that. In fact, it says the exact opposite, that AHJs have permission to ignore the written rules when they see fit.

Not directing this at you, Rob, just your comment was the closest to what I wanted to talk about.

This states that the AHJ may waive requirements, and given the lack of available products then the AHJ has ample legal ground to stand on to ignore aspects of 300.15. People always point to 90.4 when it comes to inspectors making up rules in the field, but it doesn't say that. In fact, it says the exact opposite, that AHJs have permission to ignore the written rules when they see fit.

Not directing this at you, Rob, just your comment was the closest to what I wanted to talk about.

Yes, this has been an accepted practice by inspectors for decades around here. Problem now is that more and more jobs have high paid electrical consultants who love to find things that deviate from the letter of the code. Throw in an article by Mark Ode and they'll have you installing a box in lieu of the rigid coupling. :roll: Meeting the letter of the UL listing (White book DWTT)

Meeting the letter of the UL listing (White book DWTT)

Definitions:
NPT national pipe tapered threads
NPSM national pipe straight mechanical threads

If you want to meet the requirements set forth in the UL listing for conduit fittings to join two different raceways or a raceway and cable and do not have a specific listed fitting to do that, you can do the following:

Use a cable or raceway fitting to female threads, then use a short RMC/IMC nipple*, and finally use another cable or raceway to female threads fitting. What you are doing is using a nipple rather than a coupling.

To connect a non-threaded round raceway to a threaded hub, you also use a raceway to female threads fitting, a RMC/IMC nipple and the threaded hub.

The female threads of fittings are designed to mate with NPT male threads. The male threads of fittings are designed to mate with locknuts and and have NPSM threads. Raceway threading is NPT.

Screwing NPSM male threads into a NPT female socket does not tighten up using the surface of the threads, if it does tighten up it does so by bottoming out or by a lip on the male part striking the outside of the fitting. Either way the connect is not as strong, not as resistant to coming loose, not as effective as current path, and unlikely to be water proof.

*The nipple needs to have NPT and not NPSM. An "all-threads" nipple (2 feet long, cut off chunks as you need them) does not meet the requirements. An NPSM threaded nipple may be used with locknuts and presumably bushings (since the end threads of NPT are essentially NPSM). Sierra, FM, .... those are nice tries, but leave the issues uexplained.

"There are reasons ..." More a statement of faith than an explanation.

"Watertight" .... never an issue from an electrical standpoint. NO recognized raceway is intended to be tight against liquid entry, not even the stuff called 'liquitite'. It's not as if the electricity will drip out and form a puddle.

'Taper vs. straight.' Might be time to set aside the Machinery's handbook and look at a stick of rigid. The system is deliberately intended to have straight threads on the couplings and taper threads on the pipe.

Straight to straight? There seems to be no issue with using a chase nipple with a coupling either. The joining threads on unions use straight threads. Many conduit bodies have straight threads, to accept the straight threads of EMT (or MC, or NM) connectors.

Grounding? As others have observed, there are all manner of listed fittings whose connections are far less secure than even the loosest threaded fitting.

That's why I said the UL position is illogical.