BEARINGS: BEARINGS What is Bearings..?: What is Bearings..? “A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement.” History: History The oldest instance of the bearing principle dates to the Egyptians when they used tree trunks under sleds. There are also Egyptian drawings of bearings used with hand drills. The earliest recovered example of a bearing is a wooden ball bearing supporting a rotating table from the remains of the Roman Nemi ships in Lake Nemi, Italy. The wrecks were dated to 40 AD Bearings saw use for holding wheel and axles. The bearings used there were plain bearings that were used to greatly reduce friction over that of dragging an object by making the friction act over a shorter distance as the wheel turned Why we Use Bearing..?: Why we Use Bearing..? Speed of displacement was increased Friction problems were resolved Tasks were made less difficult. Types Of Bearing: Types Of Bearing Fluid Bearings Plain Bearing Jewel Bearing Magnetic Bearing Flexure Bearings Rolling Element Bearing 1.Fluid bearings: : 1.Fluid bearings: Which solely support the bearing's loads on a thin layer of liquid or gas. They can be broadly classified as fluid dynamic bearings or hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and the pressurization is done by a pump. PowerPoint Presentation: Working Principal Uses 2.Plain bearing: : 2.Plain bearing: A plain bearing , also known as a plane bearing, no rolling elements. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion. PowerPoint Presentation: Plain Bearing Inner Side PowerPoint Presentation: Plain Bearing 3.Magnetic bearing: : 3.Magnetic bearing: It support moving machinery without physical contact. Used to in electrical meters to measure power consumption. Also used to support trains, resulting in a lower noise and smoother ride. low amount friction, run without the use of lubrication. They can also run in a vacuum, but they are very costly. PowerPoint Presentation: Magnetic bearing 4.Jewel bearing: : 4.Jewel bearing: A jewel bearing is a plain bearing in which a metal spindle turns in a jewel-lined. Low friction , Stiffness and speed. Jewel bearings are used in small instruments, but their largest use is in mechanical watches. 5.Flexure bearings: : 5.Flexure bearings: Flexure bearings are used when the load element needs to bend. Typically, flexure bearings are just one part that joins two other parts. A door hinge is an example of flexure bearings. Low friction,stiffness,limted speed. Flexure bearings: : Simple and inexpensive. Usually lightweight. Produce a low amount of friction. Generally can’t support high loads. Flexure bearings: PowerPoint Presentation: Flexure Bearings 6.Rolling Element Bearing : 6.Rolling Element Bearing Carries a load by placing round elements between the two pieces. The relative motion causes round elements to roll with very little rolling & sliding. Stiffness good , some slack Present. Speed is moderate to high. Types of rolling elements : Ball Cylindrical roller Needle Tapered roller Spherical roller Types of rolling elements Parts Of Bearing: Parts Of Bearing Cage Steel cages are stamped out of fairly thin sheet metal, much like a cookie cutter, and then bent to their final shape in a die. Balls The balls are a little more difficult to make, even though their shape is very simple. Surprisingly, the balls start out as thick wire PowerPoint Presentation: Races: Both races are made in almost the same way. Since they are both rings of steel, the process starts with steel tubing of an appropriate size. PowerPoint Presentation: ANY Question..?