New Coupling Widens Torsional Stiffness Range

W H I T E PA P E R
New Coupling
Widens Torsional
Stiffness Range
And high torque transmission in a compact
package
Engine flywheel couplings have to strike a delicate balance when it comes to
stiffness. On the one hand, they have to be rigid enough to transmit torque
efficiently and avoid resonance problems. On the other, they have to be flexible
enough to handle any misalignment between the motor and the drive shaft. A
radical new coupling design can help you strike that balance.
The Ringfeder Power Transmission TSCHAN TNR Coupling consists
of an aluminum housing and steel hub separated by a set of cylindrical
elastomer inserts. Contained in opposing machined grooves in the hub
and housing, the elastomer inserts deform under shear loads as
the coupling transmits torque.
Depending on
the application
requirements, the
coupling can have
one or two rows of
inserts, linked in series
by a grooved aluminum
buffer link.
This new coupling offers three key
design advantages over the rubber
couplings traditionally used in
stationary and mobile diesel-driven
equipment.
Tune your stiffness. The new
TNR coupling delivers a wide range
of torsional stiffness values for a
165 Carver Ave, Westwood, NJ 07675, USA
•
Toll Free: +1-888-746-4333
•
Tel: +1-201-666-3320
•
RINGFEDER TSCHAN TNR
COUPLING AT A GLANCE
•
Light weight
•
Compact
•
High power density
•
Easy maintenance
•
Low cost
•
Shock load and vibration
reduction
•
Misalignment compensation
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RINGFEDER POWER TRANSMISSION
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sales.usa@ringfeder.com
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www.ringfeder.com
W H I T E PA P E R
given coupling size. Changing the stiffness is simply a matter of varying the
arrangement and material properties of the elastomer inserts. For example,
our smallest TNR coupling can deliver dynamic torsional stiffness from 900 to
5,900 Nm/rad across a torque range of 160 to 510 Nm. That’s more than twice
the stiffness range and three times the torque range of the closest comparable
rubber couplings.
This ability to achieve many different stiffness values can be indispensable when
you need to avoid resonance issues in your powertrain designs—while keeping
the number of coupling sizes you use to a minimum. Resonance occurs when
the operating frequency of the system equals its natural frequency—which is
determined largely by the moments of inertia and stiffness of the engine, the
rotating output shaft, the couplings and the driven load. Without some sort of
damping or operating frequency adjustments, resonance can spiral out of control,
causing damaging vibrations.
Oftentimes, the application requirements will lock you into a specific engine and
set of operating frequencies. But the coupling can easily be specified with an
eye toward managing resonant frequencies and preventing your engine-driven
equipment from developing a bad case of the shakes.
That’s where the TNR coupling comes into play. By adjusting the stiffness values
you can give just the right amount of damping to ensure that the driven system’s
operating frequencies do not equal its natural frequency. Engineers have used
this strategy for years with rubber couplings, but the TNR makes it far easier to
adjust stiffness—both in terms of the granularity of the adjustment and the range
available within a given coupling size.
Manage misalignment. The TNR design also comes in handy when you need
to accommodate for any misalignment between the motor’s output shaft and
the rest of the drive train. The same elastomer inserts that allow you to dial
in a precise torsional stiffness can also provide some flexibility to offset shaft
SINGLE OR DOUBLE?
Single Row
The Ringfeder TSCHAN TNR
coupling has two different
design variations to meet the
widest possible range of torque
transmission requirements.
The single-row couplings have
just one circumferential set
of elastomer inserts around
the center hub. The doublerow couplings have two sets
separated by a buffer link. The
buffer link connects the two sets
of inserts in series, allowing
them to work together from a
mechanical standpoint. Both
designs support standard SAE
620J flange connections.
165 Carver Ave, Westwood, NJ 07675, USA
•
Toll Free: +1-888-746-4333
•
Tel: +1-201-666-3320
Double Row
•
Fax: 1-201-664-6053
RINGFEDER POWER TRANSMISSION
•
sales.usa@ringfeder.com
•
www.ringfeder.com
W H I T E PA P E R
120%
100%
Cdyn1
80%
Cdyn2
TKW
60%
TB
40%
20%
10%
10%
20%
40%
φ1
60%
φ2
80%
φ = 0º
100%
120%
φ = 20º
A given TNR coupling can achieve different torsional stiffness values
(Cdyn ) based on the elastomer inserts’ deformation behavior. (φ)
misalignment. You may have to sacrifice some torque transmission efficiency
if you pick softer elastomer inserts that can maximize the misalignment
compensation within ±0.5 degrees.
Reduce weight. TNR couplings typically weigh about 20% less than an
equivalent rubber coupling. Keep in mind, however, that equivalent means same
performance, not necessarily same size. Thanks to its wide torque and stiffness
ranges, TNR couplings have a power density advantage that often allows a
smaller, lighter model to replace a larger, heavier rubber coupling. This power
density edge can make a big difference in mobile diesel applications, such as
heavy equipment or trucks.
Save money. Over its lifetime, a TNR coupling will typically cost 15 to 25% less
than a comparable rubber coupling. This cost advantage includes a substantial
savings on initial price. And it also includes a reduction in lifecycle costs—
because replacing the elastomer inserts costs much less than replacing the
rubber elements and attached steel hubs.
For detailed technical specifications on TSCHAN TNR couplings, visit
www.ringfeder.com.
165 Carver Ave, Westwood, NJ 07675, USA
•
Toll Free: +1-888-746-4333
•
Tel: +1-201-666-3320
•
Fax: 1-201-664-6053
RINGFEDER POWER TRANSMISSION
•
sales.usa@ringfeder.com
•
www.ringfeder.com
W H I T E PA P E R
SINGLE ROW TNR COUPLINGS
DOUBLE ROW TNR COUPLINGS
165 Carver Ave, P.O. Box 691, Westwood, NJ 07675, USA • Toll Free: +1-888-746-4333 • Tel: +1-201-666-3320 • Fax: 1-201-664-6053 • sales.usa@ringfeder.com • www.ringfeder.com
RINGFEDER POWER TRANSMISSION