DMM-II DESIGN OF MACHINE MEMBERS - II III B.Tech II Semester PRESENTED BY Mohd. Makhdoom Mohiuddin

JOURNAL BEARINGS Moving parts of every machine is subjected to friction and wear. Friction consumes and wastes energy. Wear causes changes in dimensions and eventual breakdown of the machine element and the entire machine. The loss of just a few milligrams of material in the right place, due to wear can cause a production machine or an automobile to be ready for replacement. If we imagine the amount of material rendered useless by way of wear, it is startling! Lots of materials ranging from Antimony to zinc, including titanium, vanadium, iron, carbon, copper, aluminum etc., would be lost. It is therefore essential to conserve the natural resources through reduction in wear. Lubrication plays a vital role in our great and complex civilization.

BEARINGS A bearing is machine part, which support a moving element and confines its motion. The supporting member is usually designated as bearing and the supporting member may be journal. Since there is a relative motion between the bearing and the moving element, a certain amount of power must be absorbed in overcoming friction, and if the surface actually touches, there will be a rapid wear.

Classification: Sliding contact bearings Rolling contact bearings.  

SLIDING BEARINGS: . Hydrodynamically lubricated bearings Bearings with boundary lubrication Bearings with Extreme boundary lubrication. Bearings with Hydrostatic lubrication. .

ROLLING ELEMENT BEARINGS Ball bearings Roller bearings Needle roller bearings

JOURNAL BEARING: It is one, which forms the sleeve around the shaft and supports a bearing at right angles to the axis of the bearing. The portion of the shaft resting on the sleeve is called the journal. Example of journal bearings are- Solid bearing , Bushed bearing and Pedestal bearing.