Home Chapter 15 Artist's applications and bearings
Artist's applications and bearings

The artist Isabel Farnsworth created a sculpture commission titled Sharpening Device: Stones of Knowledge out of resin, bronze, brass, wood, glass, and motors.

In this work the resin wheels turn in different directions slowly with a pulley and belt system driven by two motors. This metaphoric piece combines the symbol of the grindstone and patterned images on the glass to relate branches of knowledge.


Sharpening Device: Stones of Knowledge by Isabel Farnsworth. 2002. 30”x48”x24” A public artwork commissioned by the Berea Public library in Berea, OH.


Sharpening Device: Stones of Knowledge by Isabel Farnsworth. 2002. 30”x48”x24”. Detail of drive mechanism


Bearings with notched pulleys


Bearings reduce the friction of moving or spinning components because things that roll naturally have a lot less friction than things that slide. There are several types of bearings, but ball bearings are the most common. These consist of two concentric, smooth, metal rings sandwiching a row of metal balls. The balls “bear” the load of the spinning component, such as a wheel around a shaft, and allow it to spin smoothly without a lot of wear. The outer ring transfers the load to the balls, which then transfer the load to the inner ring. The balls only make contact with small points on the surface of the rings, which allows a smooth spinning motion, but also lessens the area for bearing a load and makes the balls subject to squishing if they are overloaded.

Bearings are subject to two kinds of loading, radial and thrust, and depending on the application, they may see just one of these or a combination of both. Bearings in electric motors and pulleys see only radial loading, which comes from the tension in the belt that connects two bearings together. The bearings in a spinning stool would receive thrust loading from a person sitting and spinning, and a good example of the combination of both kinds of loading is a car wheel, which sees thrust loading from cornering and radial loading from the weight of the car.

Roller bearings use cylinders instead of balls, which increase the surface area where the roller touches the ring, and therefore increase the strength of the bearing and allow it to receive much greater radial loads. Needle bearings are roller bearings with very small-diameter cylinders that can be used in tight places.


Ball Bearings


Bushings, which are also referred to as dry bearings, have no moving parts. Bushings serve the same basic purpose as bearings and are made of “self-lubricating” metal or plastic, a material that is impregnated with oil. Bushings are less expensive and lighter weight than bearings, and can be used for low-friction applications.