Jaw Couplings vs Twin Spring Coupling
Jaw coupling is an elastomeric coupling used in a number of different industries, Industrial, distribution, agriculture to power servo motors, pumps or other motors.
The Jaw coupling is made up of 3 pieces, a input hub, a insert to absorb shock/vibration (there are 4 types of spider inserts SOX (NBR/Buna-N), Urethane, Hytrel and Bronze) and output hub.
A simple elastomeric coupling and a safety coupling as if the spider or insert fails then the 2 jaws of the input and output hub combine together to continue to work. While it will continue to run the spider which usual absorbs the vibration (dependent on the spider insert used) now not present will mean all the vibration will now be transferred to the attached equipment.
This is not ideal and means the machinery has to be stopped and coupling either replaced or a new elastomeric spider installed.
The jaw coupling is designed to run at high speed with a small angle of misalignment with some radial and axial misalignment as well. This angular misalignment is limited by 2 factors, the spider insert as the spiders are made from different materials and for specific applications.
The SOX (Buna-N) spider is softer than the Urethane spider, which is softer than the Hytrel and Bronze being a metal is the least softest. The Bronze insert can only be used in applications of 250RPM or less.
There are 2 different types of jaw type couplings, plain jaw coupling and curved jaw coupling. The main difference is the curved jaw coupling has the ability to handle higher torque loads than the standard jaw coupling but also has zero backlash, which can be accomplished with other couplings.
Jaw Coupling manufacturers
The softer the spider the quicker they wear out, so its a balance between torque and angular misalignment. Lovejoy jaw couplings are probably the most well known but as its now an old design, it is copied by a lot of different elastomeric couplings manufacturers both well known like Belden, Ruland, TB Woods, Guardian Couplings (Altra Motion),Boston Gear, SKF, Martin and any number of jaw coupling manufacturers.
With the couplings hubs, they can be anything from 1/4″ up to 2 3/8″ mismatched to fit any type of machinery but this also means that if the hubs crack or split then the required hub needs to be in stock from the supplier, and given the hubs can be made from a number of different materials, like sintered or cast iron, aluminum and stainless this adds to inventory costs to make sure the components are on hand in case of failure.
So three pieces, a central wear part (Elastomeric spider)and two hubs. Simple but it also has its disadvantages but for some users the only choice they have.
The lack of flexibility is means that if they need anything more than the 2° then they have to go to a coupling like a universal joint but the issue with that is that if they need that high speed like they get with the jaw coupling, it isn’t available unless they use a needle bearing coupling. Needle bearing uni joints top out at 6000 RPM as the bearings will wear out too quickly to be of use.
Twin Spring Coupling
So what do we offer that’s different? Well in a way we offer the advantages without the disadvantages
The Jaw coupling is a high speed coupling, so is the Twin Spring Coupling, both are able to run in excess of 7000 RPM, but the Twin Spring Coupling doesn’t have a spider insert to absorb vibration, the twin spring design absorbs that.
Twin Spring Coupling’s design is a one piece design, the hubs used in a jaw coupling are integrated into the coupling, so its still acts a safety coupling with no elastomeric spider that needs to be replaced.
Our couplings have the same torque outputs as the most commonly used jaw couplings and can run at the same speeds.
Twin spring design uses torsion springs which makes them have high torsion rigidity, verse similar to the jaw type couplings which means at low angular misalignment the same coupling characteristics can be achieved.
The main difference is the twin springs design allows an increase in flexibility up to 15°, so this allows the coupling to be more flexible than a standard jaw coupling so an increase in angular misalignment.
Standard jaw couplings equivalents
Lovejoy L150, Boston Gear FC38, FC45, SKF FRC180 are equivalent to the TSC300 with SOX HBR and Urethane spiders and TSC500 with Hydrel and Bronze spiders.
Lovejoy AL150, Boston Gear FC25, FC30, FC38 & SKF FRC150 are equivalent to the TSC150
Lovejoy L190, Boston Gear FC38, FC45 and SKF FRC300 are equivalent to the TSC300 with SOX HBR and Urethane spiders and TSC500 with Hydrel and Bronze spiders.
Lovejoy L225, Boston Gear FC38, FC45 and SKF FRC300 are equivalent to the TSC300 with SOX HBR and Urethane spiders and TSC500 with Hydrel and Bronze spiders.
Lovejoy L226, Boston Gear FC45 and SKF230 is equivalent to the TSC500
Lovejoy C276 is equivalent to the TSC500 with SOX HBR spider
Curved Jaw couplings equivalents
Lovejoy CJ 38/45 is equivalent to the TSC300 – Urethane Spider – 92 Shore A (Yellow),Urethane Spider – 80 Shore A Sizes 14 – 38 (Blue)
Lovejoy CJ 42/55 is equivalent to the TSC500 – Urethane Spider – 92 Shore A (Yellow),
Lovejoy CJ 48/60 is equivalent to the TSC500 – Urethane Spider – 92 Shore A (Yellow),
The main value in replacing the Jaw coupling either the standard jaw type or a curved type coupling is the increase in angular misalignment, no spider insert that needs to be replaced and its one piece design verses that of three pieces in a jaw coupling make Twin Spring Coupling a great alternative for jaw coupling to run servo motors etc.
For more information on all our products go to https://twinspringcoupling.com/coupling-products/