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Unlike many other torque control devices, Magtrol hysteresis
devices provide absolutely smooth, infinitely controllable
torque loads, independent of speed, and they operate without
any physical contact of interactive members. As a result,
with the exception of shaft bearings, there are no wear components.
This provides such advantages as: longer expected life, superior
torque repeatability, life cycle cost advantages, broad speed
range, excellent environmental stability, and superior operational
smoothness.
| Long, Maintenance-Free Life |
Magtrol hysteresis brakes
and clutches produce torque strictly through a magnetic
air gap, making them distinctly different from mechanical-friction
and magnetic particle devices. As a result, hysteresis
devices typically have life expectancies many times that
of friction and magnetic particle devices. |
| Life-Cycle Cost Advantages |
While the initial cost
of hysteresis devices may be the same or slightly more
than that of their counterparts, the high cost of replacing,
repairing and maintaining friction and magnetic particle
devices often makes hysteresis devices the most cost-effective
means of tension and torque control available. |
| Excellent Stability |
Magtrol hysteresis devices
can withstand significant variation in temperature and
other operating conditions. In addition, because they
have no particles or contacting active parts, hysteresis
brakes and clutches are extremely clean. Magtrol devices
are used in food and drug packaging operations, in clean
rooms, and environmental test chambers. |
| Superior Torque Readability |
Because torque is generated
magnetically without any contacting parts or particles,
hysteresis brakes and clutches provide superior torque
repeatability. Friction and magnetic particle devices
are usually subject to wear and aging with resultant loss
of repeatability. Magtrol devices will repeat their performance
precisely, to ensure the highest level of process control. |
| Broad Speed Range |
Magtrol hysteresis devices
offer the highest slip speed range of all electric torque
control devices. Depending on size, kinetic power requirements
and bearing loads, many Magtrol brakes can be operated
at speeds in excess of 10,000 rpm. In addition, full
torque is available even at zero slip speed and
torque remains absolutely smooth at any slip speed. |
| Operational Smoothness |
Because they do not depend
on mechanical friction or particles in shear, hysteresis
brakes are absolutely smooth at any slip ratio. This feature
is often critical in wire drawing, packaging and many
other converting applications. |
Magnetic Particle Brakes and Eddy-Current
Brakes
Hysteresis Brakes are often confused with magnetic particle
brakes and eddy current brakes, both of which operate and perform
differently than Hysteresis Brakes.
| Magnetic Particle Brakes |
Eddy Current Brakes |
| Unlike Hysteresis
Brakes, magnetic particle brakes have a free flowing metal
powder in the air gap. When a magnetic particle brake
is energized, the particles form chains along the magnetic
field lines linking the rotor to the housing. As the rotor
rotates, the chains continuously shear, generating torque
and heat. While magnetic particle brakes are capable of
producing high torque, the friction between the particles
can result in poor stability and repeatability, along
with a high residual drag. |
Eddy current
brakes develop torque by the direct magnetic linking of
the rotor to the stator. This linking generates eddy currents
in the driven rotor. Eddy current brakes must have a slip
between the rotor and the stator to generate torque. |
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