Page 4 - Industrial Technology Extra - 26th May 2020

TORQUE LIMITERS...

Reliable cutterhead protection

EAS-HT torque limiting clutches by Mayr Power Transmission prove their worth in
tunnel boring machines around the globe. These clutches are actuated reliably and
traceably, and sustainably protect the drive components from overload damage.

unnel boring machines work their
way through the mountain like
moving factories underground.
TAnd every single metre counts.
An overload case for example – caused
through irregularities in the rock – must
not stop the gigantic drills.
“If our EAS-HT torque limiters
disengage on the construction site, then at
a defined and traceable torque and only in
order to protect the motor, gears and drive line of
the cutterhead from damage through overload,” torque results from the pre-tension force of the
explains Ralf Epple, product manager at Mayr elements multiplied by the number of elements and
Power Transmission in Mauerstetten. the radius at which the individual elements are
In this way, long downtimes can be avoided and arranged.
the machines can be sustainably operated. "The Due to the modular concept, not only clutches
safety concept must not be susceptible to tailored to the respective application case can be
manipulation", emphasizes Epple. "This means that built, but also far higher torques can be managed
the torque on our clutches is set manufacturer-side than with a central disengagement mechanism.
and is immediately accessible again after Mayr offers the torque limiters from the EAS-HT
disengagement. The safety aspect is not dependent construction series in a standard version with a
on recommissioning. The torque limiting clutches torque of up to 440,000 Nm. However, the limits of
work reliably." what is possible have not yet been reached: Thanks
to the modular construction, the possibilities are
Protection at extremely high torques endless.
“The disengaging EAS-HT clutches are element On the EAS-HT torque limiters, the individual
clutches which represent the ideal solution for overload elements transmit the torque through
extremely high torques and speeds or large mass positive locking during functional operation. In case
moments of inertia,” explains Epple. These clutches of overload, they separate the input and output
are based on individual overload elements which faster than any control unit in less than 5 ms almost
are integrated into the flanges. The achievable residual torque-free with high switch-off and

May 2020 • INDUSTRIAL TECHNOLOGY EXTRA! • p4