An electrical device, a ball bearing motor works on thermal energy, spinning in response to being kick-started with high currents. This is a commercially useless motor that only has value from the viewpoint of understanding scientific principles. It's a very simple motor that consists of a flywheel and two ball bearing assemblies mounted on a conductive shaft. The ball bearing motor is connected to a source of electrical power, which can either be alternating or direct current. It is capable of spinning in either direction depending on how it started initially and can spin very fast if given enough power.
This motor can be very easily constructed with parts salvaged from junked mechanical devices like copy machines and printers. All that's required are two ball bearing races and a shaft that fits closely inside them. The outer rings of the races are connected to a high current source having a low voltage. Power sources like mains transformers, car batteries, and 12-volt jump starter packs are ideal. The power source should have a peak power rating of a couple of hundred amperes and should be able to supply that power for a reasonable amount of time.
The shaft in the ball bearing motor should have enough leeway to turn freely, and it should ideally spin for a minimum of three revolutions if turned lightly by hand. In order to act as a flywheel, the ball races must fit inside a metal tube, which is mounted on a nonconductive shaft. If the shaft doesn't fit well enough inside the ball race, then it can be jammed using a little aluminum foil. A good, tight fit ensures that the electrical contact remains stable, and care should be taken that the mechanism is free from grease so that it turns freely.
When power is supplied to the ball bearing motor, it flows through the outer ring of one ball race and through the ball bearings into the inner race. The power then flows down the conductive shaft and flows into the inner race of the second ball bearing. It passes through these ball bearings and the outer ball race and returns to the power source. The ball bearing motor only begins to rotate in a particular direction when it is given an initial spin in that direction. It rotates because heat is generated locally that causes the ball to expand and slightly elongate.
The ball pushes against the inner and outer rings, and because the bearing is rotating from the spin given to it, the ball is pushed around in the direction of motion. All the balls that are in contact with both rings sustain the rotation, and the motor begins spinning faster. If the power supplied is high and resistance of the setup is low, the motion of the ball bearing motor begins to accelerate very rapidly. It can reach very high speeds, of around 1000 rpm, and both wires and motor can get extremely hot. Safety precautions should be taken to protect against any potential hazards, and wearing eye and face protective devices is recommended.