Brakes and Clutches
Large Bore Brakes

Large Bore Brakes

SpecificationsApplicationsData SheetManual

Large BoreFor many years Magtrol has designed Hysteresis Brakes with large bores, and without a shaft or bearings. These brakes are used for superior tension control for helical wrapping, braiding and other feed through applications. Magtrol Large Bore Brakes are used in machines for manufacturing cable, wire, fiber optic cable, rope and tape, among others. Magtrol Large Bore Brakes provide smooth, repeatable torque, largely independent of
speed. Maximum speeds up to 8000 rpm are available.

These brakesconsist 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.

The pole/case assembly and rotor are available are manufactured in standard bore sizes
and hole patterns. Variations to the standard dimensions can be made based on customer requirements. Certain modifications to the brake, such as a larger bore dimension, may impact its performance ratings.

Additional options available include rotor mounting flanges, power supplies, torque-current curves and other coil voltages. Contact Magtrol for more information.

Operating Considerations
Alignment Notes
  • The pole/case assembly and the rotor are shipped as separate items.
  • It is the responsibility of the machine designer to assure proper alignment of the mating brake parts in the final assembly.
  • These components must be mounted so that the concentricity and perpendicularity between the rotor and pole does not exceed the specified tolerances.
  • Refer to individual LB model drawings for further details.
Additional Information

At the standard bore diameters, actual brake torque at rated current will normally exceed the minimum guaranteed values. Larger bore diameters can be provided, however, reductions in performance will result as bore diameters are increased. Any modification to a large bore brake should be reviewed in detail with Magtrol before ordering.

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For complete technical specifications and a general dimension drawing, download the data sheet. For detailed dimension drawings… Calculators
Click on the icon in the table below. A PDF document will open in a new window.
(Adobe Acrobat Reader 7.0, or later, is required.)
Model Minimum
Torque at
Rated Current
Kinetic Power** View
Solid Model
5 Minutes Continuous
LB-250M-2 1,50 270 3000 450 110 NA
LB-450M-2 3,00 442 2500 670 160
LB-750M-2 5,00 383 2000 1000 200
LB-1750M-2 12,00 500 1800 1200 350
* Higher speeds available on special basis.
** Kinetic power ratings are maximum values based on limiting coil and/or bearing temperature to approximately 100 ºC, and should not be exceeded. Actual values in service may vary ±50% depending on mounting, ventilation, ambient temperature, etc.
***Standard coil voltage is 24 VDC. 90 volt and non-standard coil voltages are available. 12 VDC coils are available on LB-250M through LB-750M models.
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The straightforward design of Magtrol Hysteresis Brakes and Clutches has made them ideal for unique applications requiring special equipment interface or mounting configurations, such as our Large Bore Brakes, which are widely used on special equipment for helical wrapping and braiding operations.
Helical Wrapping Typical helical wrapping operation in which a rotating spindle winds onto a laterally moving core with the supply reel tension being controlled by a Magtrol Hysteresis Brake.
Flyer Control Flyer Control: The brake pole/case assembly is bolted to the machine frame and a hollow shaft, with bearings, is mounted in the pole. The hollow shaft, rotor and flyer bobbin form one assembly to tension the winding material.
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Magtrol, Inc (USA): 716-668-5555 • ~ Magtrol SA (Switzerland): 41 (0)26 407 3000 • ~ Magtrol India: 91 (0)80 6561 395 7·
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