TecKnow of the day
The invention of the rolling bearing, in the form of wooden rollers supporting, or bearing, an object being moved is of great antiquity, and may predate the invention of the wheel.
The term “bearing” is derived from the verb “to bear”; a bearing being a machine element that allows one part to bear (i.e., to support) another.
There are many applications where a more suitable bearing can improve efficiency, accuracy, service intervals, reliability, speed of operation, size, weight, and costs of purchasing and operating machinery.
Thus, there are many types of bearings, with varying shape, material, lubrication, principle of operation, and so on. There are at least 6 common types of bearing, each of which operates on different principles:
◾Plain bearing, consisting of a shaft rotating in a hole. There are several specific styles: bushing, journal bearing, sleeve bearing, rifle bearing, composite bearing.
◾Rolling-element bearing, in which rolling elements placed between the turning and stationary races prevent sliding friction. There are two main types •Ball bearing, in which the rolling elements are spherical balls
•Roller bearing, in which the rolling elements are cylindrical rollers
◾Jewel bearing, a plain bearing in which one of the bearing surfaces is made of an ultrahard glassy jewel material such as sapphire to reduce friction and wear
◾Fluid bearing, a noncontact bearing in which the load is supported by a gas or liquid,
◾Magnetic bearing, in which the load is supported by a magnetic field
◾Flexure bearing, in which the motion is supported by a load element which bends.
Bearings played a pivotal role in the nascent Industrial Revolution, allowing the new industrial machinery to operate efficiently. For example, they saw use for holding wheel and axle to greatly reduce friction over that of dragging an object by making the friction act over a shorter distance as the wheel turned.
Today ball and roller bearings are used in many applications which include a rotating component. Examples include ultra high speed bearings in dental drills, aerospace bearings in the Mars Rover, gearbox and wheel bearings on automobiles, flexure bearings in optical alignment systems, bicycle wheel hubs, and air bearings used in Coordinate-measuring machines.