Large Bore and Matched Large Bore Brakes LB / MLB Series0 pages

M AGTROL

LB/MLB
Data Sheet

LB Large Bore Brakes and
MLB Matched Brakes
FEATURES
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Torque up to 12 N·m
Speed up to 3000 rpm (higher speeds available)
Power up to 1200 W
No shaft or bearings: ideal for feed-through applications
Torque independent of speed
Long, maintenance-free life
Operational smoothness
Superior torque repeatability
Broad speed range
Excellent environmental stability

Pole/Case Assembly

Rotor

DESCRIPTION
For many years Magtrol has designed hysteresis brakes with
large bores, and without a shaft or bearings. These uniquely
designed brakes contain a large inside diameter to accommodate
wire fed directly through the brake, while the rotor mounted to
a tape supply reel, provides the required tension.
Magtrol Large Bore Brakes consist of two primary parts: a
pole/case assembly and a rotor. The pole/case assembly is
usually mounted in a stationary position within the machine,
while the rotor is shaft-mounted concentrically within the
pole/case assembly.
As with all of Magtrol’s hysteresis devices, LB/MLB Series
Brakes operate without the use of magnetic particles or friction
components. This provides absolute smoothness, superior
torque repeatability, quiet operation and a long, maintenancefree life.

MATCHED BRAKES
In tension control applications that have multiple webs or
multiple strands, it is very desirable to match the tension
of each web or
Matched Brakes
Regular Brakes
strand. This is most
Brake
Brake
commonly attained
Power Supply
Transducer
Power Supply
Transducer by using a closedloop servo control
Brake
Brake
system which
controls current to
Power Supply
Transducer
Brake
a braking device
Brake
Brake
through the use
of dancer arms,
Power Supply
Transducer
Brake
follower arms and
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in-line tension transducers. The problem with such systems
is that each web or strand must be individually controlled,
increasing the cost and complicating the system with multiple
sensors and power supplies.
To solve this problem, Magtrol developed a system to
assure that every brake of a given model designation will be
matched—at a predetermined torque and current point—to
other brakes of the same model designation. Regardless of
material and manufacturing tolerances, each brake is matched
at the selected match point to within a tolerance of ±1%. The
maximum deviation in torque from brake to brake at any
point along their torque/current curve (from 0 torque up to
the selected matched torque point) is less than ±4% of the
selected matched torque value. With this level of matching,
a system with multiple tension rollers would provide tension
consistency within ±1% if set at the matched point with all
brakes receiving the same current. The matched point can be
any value between 50% and 100% of rated torque, which
allows the brakes to be optimized for specific applications.

APPLICATIONS
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Helical wrapping, braiding and other feed-through
applications—used in machines for manufacturing cable,
wire, fiber optic cable, rope and tape
Flyer control in winding operations

www.magtrol.com