Best Industrial power transmission couplings for 2021
The best industrial power transmission couplings for the mass industrial market are broken roughly into these 5 types of couplings, some have subsets as well, the elastomeric couplings have jaw couplings as segment where some people treat them as a category by themselves. These couplings are also constructed of different materials, the cheapest couplings are made of steel, where the more expensive ones are made of alloy and the most expensive, stainless steel.
Lets break these couplings down and see what could be a better coupling in the application they are used in.
- Certainly the most well known coupling, its design goes back to the 1678 Hooke joint (invented by Robert Hooke) The universal joint is made up of 3 components, a input shaft, an output shaft and the central bearing cross or block (dependent on the style of universal joint used. The block and pin universal joint is as it sounds a rounded cube like centre piece with 2 holes one vertical the other parallel which allows pins to attach the input and output shafts or “hub” and the block together. This allows the coupling to be able to pivot. The issues faced by the block and pin universal joint is heat, as it is used it expands.
This means reduced speed as the heat created makes the block and pins expand, causing binding of the pins inside the block, accelerating block and pin wear leading to failure and replacement. This reduced speed makes this universal joint only good for use at 1000RPM.
The other universal joint uses needle bearings to make the coupling flexible, it also makes it more delicate and complicated to use and maintain. The needle bearing universal joint has a bearing cross, this metal holder or cross that holds the needle bearings in 4 locations, 2 each for the input and output hub or yokes. These bearings fit inside a hole in the input and output yokes and the bearing cross sometimes (dependent on the model) contains a grease nipple or “zerk” so that grease can be added and this grease presses out into the needle bearings, extending their lifespan.
The downside is that if grease isn’t added, these bearings will wear quicker due to a number of factors, a. How fast they are being used, b. What angle the universal joint is being used at c. what kind of application the universal joint is being used in.
Needle bearing universal joints have a life expectance that revolves around these 3 factors.
1.The RPM the coupling is used at will dictate the amount of heat created by the joint, while the block and pin is effected more than the needle bearings, they also develop heat and why the application and reapplication of grease is so important. 2. The larger the angle of misalignment the increased wear factor of the needles inside their “cage” and the quicker the bearings will need to be replaced. 3. So applications demand alot from the universal joints, either large initial startup torque, stopping and starting, variations in the angle of misalignment (changing constantly as in a conveyor belt)
These 3 factors mean while it can handle more torque and higher speed, it comes at the price of increased maintenance and monitoring to ensure the universal joints dont fail.
Elastomeric Couplings/ Jaw Couplings
- Elastomeric couplings are a diverse offering, jaw couplings and curved jaw couplings are the most well known, an elastomeric coupling is basically a flexible insert between a input and output shaft, while very robust have a very limited range of misalignment either angular and parallel. In the mass market jaw couplings are the most widely used, and used with things like servos, motors and pumps. Lovejoy Jaw couplings are probably the most well known, but the design is now made all over the world now by different coupling manufacturers like Boston Gear FC range, SKF FRC range, Rexnord jaw couplings.
The jaw coupling like the universal joint is made up of 3 components, a input and output hub and a elastic insert or “spider” due to its shape. The spider is used to sit between the jaws of the two hubs and absorbs the vibration of the two hubs and their differing angles. The wider that angle the faster the wear on the spider, especially at the edges and legs. Once the insert has worn back to allow the metal hubs to touch, vibration increases and wear of the hubs increases.
This means the coupling needs to be disassembled and the insert replaced. This is a fundamental issue with the jaw couplings that they are only to be used in a set range of misalignment, anything outside of that leads to premature wear and increased vibration.
Beam Couplings – Whether a single beam or multiple beam, the beam coupling is a simple one piece coupling, its use is for servos and motors. They are small with the ability to handle only small amounts of torque and only a few degrees of angular misalignment. The single beam coupling is a cylinder of steel or alloy with cuts made on either side which allows it to flex, multiple beam coupling is a longer cylinder with more cuts in it to allow more angular misalignment. Since the cylinder is cut numerous times its ability to handle any degree of torque is compromised.
Bellows Coupling – Bellows couplings are one piece corrugated metal couplings. With no real give in their design, they can only like a jaw coupling and beam coupling has a few degrees of misalignment. With the bellows being made from one piece of metal these couplings are a high speed coupling, but its downside is it has the ability to transmit a very small amount of torque.
Spring Coupling – Spring couplings unlike the twin spring coupling is a series of springs joined together but the springs thickness is very small which means the ability to transmit torque is low. The Uniflex range by Lovejoy is the only spring coupling available to the industrial marketplace.
Twin Spring Couplings
What are the Best Industrial power transmission couplings for 2021
Each coupling have been around for decades in some cases centuries.
How is Twin Spring better?
Twin Spring Couplings is a simple design but without the downside of other industrial couplings.
Universal Joint – It transmits large amounts of torque and is the most flexible of the couplings on the market, but the maintenance is something that works against it. The components are cheap but when constantly needing to be replaced plus the cost of labor and the loss of revenue due to machinery not being utilized makes it an expensive coupling
Jaw couplings – Capable of large amounts of torque, the small angular misalignment and elastomeric insert limits the amount of applications it can be used in, as the wear out of the spider inserts means increased labor costs to replace them as well as the disruption to equipment usage.
Beam couplings – Due to their small size and the ability to only carry such a small amount of torque, their high speed is the only real reason they are used, whether single beam or multi beam couplings, as a servo coupling the twin spring coupling can replace these couplings.
Bellows couplings – A servo coupling much like the beam coupling, it is slightly more flexible can take more torque but as another servo coupling is limited by the amount of angular misalignment it can achieve, normally 5° or less
Spring Couplings – While flexible they are made up of multiple small diameter springs, which means they cannot carry much torque, where the Twin Spring Coupling is more flexible it can also transmit more torque at a higher RPM
Twin Spring Coupling is flexible up to 45°, can carry up to 6000 in lbs. of torque, contains no internal components that wear out with use, is a one piece design so no replacement of any components like other couplings. Its alloy construction means it is long lasting, corrosion resistant (Stainless steel models are available on request). It is available to replace conveyor universal joints, attachment universal joints, Industrial Lovejoy type universal joints, jaw couplings, elastomeric couplings, single and multiple beam couplings, Bellows couplings and spring couplings.
How does it work? Why is it so different, look at our page on how it works and you will see how different it is and what it can do for you to change your industrial couplings, whether they be Lovejoy, Ruland, Dodge, Altra Motion, Belden, TB Woods, Helical or R+W
See our product range of industrial couplings, the TSC150 (1800 in lbs. of static torque), TSC300 (3600 in lbs. of static torque) and the TSC500 (6000 in lbs. of static torque)
Not an industrial company? Then look at the range of couplings for Farming (PTO and attachment couplings), Automotive couplings (Spicer Uni joints) and Mining Couplings (conveyor belts and underground mining equipment. Click here for more information on them https://twinspringcoupling.com/coupling-products/
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