Product category:
Gears, brakes, couplings and engines
News Release from: R+W Coupling Technology | Subject: BKL series
Edited by the Engineeringtalk Editorial
Team on 30 August 2002
Budget bellows offer best of both
coupling worlds
Bellow couplings are both flexible and torsionally stiff.
When specifying a shaft coupling for a servo or stepper application, while it is important to have flexibility, it is the torsional stiffness that really becomes an issue in tightly controlled motion systems While spiral cut helical couplings are often the first coupling considered for low to medium torque applications, bellow couplings are more often the best coupling for the job
This article was originally published on Engineeringtalk on 23 Jun 2008 at 8.00am (UK)
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Coupling flexibility protects bearings from lateral loads occurring as a result of sight shaft misalignments, whereby increasing the service life.
With that being the case, why not just look for the most flexible coupling available? Because the most flexible couplings are also the least torsionally rigid.
While helical couplings are so flexible that they could conceivably be used as a U-joint, in most cases that kind of excessive flexibility is not necessary.
The net effect of this is increased system wind-up, caused by a twisting motion in the coupling at starts, stops and load reversals.
This in turn makes for long settling times that reduce the speed of the system.
The solution is to use a coupling that is both flexible and torsionally stiff.
Bellow couplings are exactly that.
While flexible enough to compensate for shaft misalignments typical of most motion control systems, bellow couplings are also extremely torsionally stiff.
In many cases they can be as much as 100 times more stiff than a helical coupling of a comparable torque capacity.
In the past, a great reason not to use bellow couplings in many cases was their high cost in comparison with a helical style.
This is no longer a problem.
R+W Coupling Technology has recently released the BKL series of economy bellow couplings.
Using standardisation of componentry and ease of assembly, R+W is now making bellow couplings an option where they once were not.
While helical style couplings are very flexible, it is important not to neglect other benefits associated with the use of a flexible shaft coupling.
The best way to achieve the optimum performance capabilities of a motion control system as far as a coupling is concerned, while maintaining a long service life, and minimising costs, bellow couplings are clearly the way to go.
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