A ball bearing motor or ball-race motor is an

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

consisting of two

ball bearing A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...

s assembled on a

conductive In physics and electrical engineering, a conductor is an object or type of material that allows the flow of Electric charge, charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. The flow ...

common shaft with provision for passing

electric current An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge c ...

between two outer bearing races. The motor is usually not self-starting and must be given an initial rotation to start. When a large current is passed through the device, an electromechanical effect, called Huber effect, causes the motor to maintain the rotation. The effect is a complex physical phenomenon, its nature was still subject of a scientific debate in the early 2020s. A

macroscopic scale The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible with the naked eye, without magnifying optical instruments. It is the opposite of microscopic. Overview When applied to physical phenom ...

ball bearing motor is "completely impractical", as heating (due to very low

efficiency Efficiency is the often measurable ability to avoid making mistakes or wasting materials, energy, efforts, money, and time while performing a task. In a more general sense, it is the ability to do things well, successfully, and without waste. ...

) and sparking will cause it to self-destruct in seconds if operated in the air.

History

Huber effect

Jacob Huber had discovered the electromechanical effect in 1959. Huber investigated wheelsets moving on rails when he discovered an

eponymous An eponym is a noun after which or for which someone or something is, or is believed to be, named. Adjectives derived from the word ''eponym'' include ''eponymous'' and ''eponymic''. Eponyms are commonly used for time periods, places, innovati ...

effect: if a voltage differential is applied to the rails (and a large electric current passes from one rail to another through the wheelset) then the initial rotation of the wheels causes a force to appear that supports the initial motion. Huber assumed the force to have an

electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...

nature, but it is not borne out by the experimental results (the force does not depend on either the direction of motion or

electric polarity The following outline is provided as an overview of and topical guide to electrical polarity (also called electric polarity). Positive and negative polarity * In electrical engineering, electrical polarity defines the direction in which the el ...

of the current).

Ball-bearing motor

A ball-bearing implementation spinning at 1000 RPM was made by R. A. Milroy in December of 1959 (unaware of Huber's work at the time, published in 1967). Kosyrev et al. in 1963 proposed a single-bearing design where the voltage is applied to the inner and outer tracks.

Explanation of Huber effect

There are multiple explanations of the effect, see the large bibliography in McDonald's work. In 1965 Electronics and Power magazine published a letter by RH Barker asking for an explanation of how this type of motor worked. At the time various explanations had been offered. S. Marinov suggests that the device produces motion from electricity without magnetism being involved, operating purely by the resistance heating causing an asymmetric thermal expansion of the balls in the bearings as they rotate. The same explanation is given by Watson, Patel and Sedcole for rotating cylinders (instead of balls). However, H. Gruenberg has given a thorough theoretical explanation based on pure electromagnetism (and neglecting the thermal effects completely). Also, P. Hatzikonstantinou and P. G. Moyssides claim to have found an excellent agreement between the results from the electromagnetic theory and the experiments measuring the total power and efficiency of the motor.

References

Sources

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External links

The Ball-Bearing electric motor
{{Electric motor Electric motors Rolling-element bearings