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Unbalanced Motors

Unbalanced motors can be used as drives for almost each case of application in the vibration feeder technology and over all industries. Unbalanced motors are the prefered drive system, in particular if it depends on high throughput of bulk material.

Examples for applications:
  • Bunker extraction
  • Dewatering
  • Classifying
  • Dedusting
  • Screening
  • Conveying of high quantities of bulk materials
  • Compacting
  • Dosing
  • Loading
  • Cooling
  • Heating and drying

They ensure as single used vibrator motors for a smooth flow of material in:

  • Silos and bunkers
  • Deflection grills
  • Downspouts and chutes
  • Filter and filling plants

Unbalanced motors are suitable as drives for vibration conduits and pipes, vibrating and bar grate filters, vibration funnels and vibrating tables, worm conveyors or water removal equipment. As vibrators for silos, bunkers, deflection grills, downspouts, chutes, filter, filling plants, they guarantee a smooth material flow. Whether in gravel drainage, screening, dedusting or filters, with the conveying of large volume quantities or in case of special tasks involved in process engineering, such as e.g. concrete compaction, dosing and material loosening, AViTEQ unbalanced motors perform their work reliably in every case. Take advantage of our more than 50 years of experience in vibration conveying technologies in all sectors.

Advantages of the AViTEQ unbalanced motors

  • Operationally safe in continuous employment
  • High level of performance with compact dimensions
  • Efficiency
  • Latest state-of-the-art of production engineering
  • Conformity with all EC Guidelines which affect the drives
  • Also available for explosion-endangered spaces (Ex), as well as for 60 Hz power systems and other mains voltages

Construction and operating mode

The unbalanced motor is a three-phase ac induction motor, on which weights are eccentrically attached at the ends of the running shaft; so-called eccentric weights (flyweights).

Centrifugal forces are generated with rotating waves. The value of these centrifugal forces can be changed by adjustment of the flyweights while the motors are at standstill. The centrifugal forces which the motor generates displace the working device (conduit, table, shaped form) and the conveyed material mass by means of vibrations.

Drive selection

The value of the centrifugal force generated, the operating frequency and the mass of the equipment to which unbalanced motors are securely bolted, determine the size of the vibration amplitude (double amplitude). The forces transferred by the motor to the working device can be calculated very simply from the acceleration values at the respective operating frequencies and the vibration amplitude. You can read off the vibration amplitude for all AViTEQ motors, depending on the effective weights, in our reference pamphlet. In this way, you can rapidly find the optimum drive. The vibration amplitude defines the maximum height of the microthrow and thus the theoretically possible conveying speed. The actual conveying rate is basically influenced by the conveying cross-section, the settled-material density and the conveyability of the bulk material.

With working torques of 0.1 kg.cm to 2763 kg.cm and centrifugal forces up to 119 kN, AViTEQ unbalanced motors can move devices of more than 11,000 kg dead weight.

The vibration amplitude Sn is limited in practice, on the one hand, by the acceleration which the working device can withstand (service life) and, on the other hand, on the standstill condition of the conveyed material caused by an acceleration value that is too low.


Deviating data for unbalanced motors for connection to 265/460V, 60Hz power supply, see reference pamphlet VIB.2.56 Arrangement of the Motors. In the case of unbalanced motors, elliptical, circular or rectilinear vibration movements of the working device can be generated, according to arrangement.

  • Double drives, which are counterrotating and synchronous rotating, generate a linear vibration movement; for example, in the case of vibration conduits or pipes.
  • Individual drives, which are arranged at the center of gravity, generate a circular vibration movement; for example in the case of filters.
  • Individual drives, which are arranged outside of the center of gravity, result in an elliptical vibration movement; for example for the shaking of bunkers.

Construction notes for working devices

The installation of the motors must be implemented on a flexurally-resistant drive part, since otherwise there is a danger of breaking and the motors cannot synchronize themselves automatically. Large-scale damages can result for the working user device after operation with incorrect rotation direction, even if it is only for a short period. In the case of large, long conveyors a transverse vibration monitoring, which also has an incorrect rotation direction, is employed. A vibration device is built correctly if a maximum stiffness is achieved at low weight. Low weight and large levels of stiffness are not inconsistent requirements if the bracings are provided with suitable ribbed reinforcement.

© 2009 AViTEQ Vibrationstechnik GmbH