Category: Bearing

Engine Bearing | Structure of Engine Bearing

Engine bearing

         The crankshaft if supported by bearing. The connecting rod big end is joined to be crank pin on the crank of the crankshaft through a bearing. A piston pin at the rod small end is accustomed attaching the rod to the piston. The piston pin drives in bearings. Everywhere there is rotating action in the engine, bearings are accustomed supporting the moving parts. The presence of bearing is to decrease the friction and to allow the parts to move easily. Bearings are lubricated with oil to make the relative motion easier.Bearings used in engines are of two types : sliding or rolling

01 - Bearings present in engine - types of bearings

            The sliding type of bearings are sometimes called bushings or sleeve bearings because they are in the shape of sleeve that fits around the rotating journal or shaft. The sleeve-type connecting rod big end bearings usually called simply rod bearings and the crankshaft supporting bearings called the main bearings are of the split sleeve type.

01 - engine bearings - types of bearings

         They must be split in order to permit their assembly into the engine. the upper half of the rod bearing is fitted in the rod, the lower half is mounted in the rod bearing cap. When the rod cap is fastened to the rod shown in the picture complete sleeve bearing is formed. Likewise, the upper halves of the main bearings are assembled in the engine and then the main bearing caps, with the lower bearing halves are attached to the engine to complete the sleeve bearings supporting the crankshaft.

Structure of a bearing

        The typical bearing half is made of steel or bronze back to which a lining of relatively soft bearing material is applied. This relatively soft bearing material, which is made of several materials such as copper, lead, tin and other metals, has the ability to conform to slight irregularities of the shaft rotating against it. If wear does take place, it is the bearing that wears and the bearing can be replaced instead of much more expansive crankshaft or other engine part.

01 - bearing structure - structure of engine bearing

              The rolling-type bearing uses balls or rollers between the stationary support and the rotating shaft. Since the balls or rollers provide rolling contact, the frictional resistance to movement is much less. In some roller bearings, the rollers are so small that they are hardly bigger than needles. These bearings are called needle bearings. Also some rollers bearings have the rollers set at an angle to the races, the rollers roll in are tapered. These bearings are called tapered roller bearings. Some ball and roller bearings are sealed with their lubricant already in place. Such bearings require no other lubrication. Other do require lubrication from the oil in the gasoline or from the engine lubrication system.

        The type of bearing selected by the designers of the engine depends on the design of the engine and the use to which the engine will be put. Generally sleeve bearings, being less expensive and satisfactory for most engine application. Infact sleeve bearings are used almost universally in all automobile engines. But you will find some engine with ball and roller bearings to support the crankshaft and for the connecting rod and piston-pin bearings.

Bearings | Types Of Bearings | Bearings Online


A bearing is a machine element that constrains relative motion between moving parts to only give the desired motion. The design of bearing may be provide for free linear movement of the moving parts or free rotation around a fixed axis or it may prevent motion by controlling the vectors of normal forces that bear on the moving parts .They are mainly used to minimize the friction between moving parts.

The invention of the rolling bearing, within the sort of wood rollers supporting, or bearing, associate object being affected is of nice antiquity, and may predate the invention of the wheel. The ball bearing was originally described by GALILEO in the 17th century.

01-bearings-sealed ball bearings-high temperature bearings

Bearings played a significant role in technological revolution allowing the new industrial machinery to work with efficiency. There are various types of bearings. The most common bearing is plain bearing which uses lubricant between the rubbing surfaces.

Types of bearings:

  • Plain Bearing
  • Journal bearing
  • Sleeve bearing
  • Rolling element Bearing
  • Jewel Bearing
  • Fluid Bearing
  • Magnetic Bearing
  • Flexure Bearing
  • Common motions permitted by bearing are as follows

    • Axial Rotation
    • Linear Motion
    • Spherical Rotation
    • Hinge Motion

    Bearings are designed on the basis of the following subjects

    • Friction
    • Speeds
    • Loads
    • Purpose
    • Stiffness
    • Life

    Maintenance and Lubrication of a Bearing is very important. The external factors that effect a bearing are electrical signals, temperature,exposure to environment. To prevent bearing from these external factors they should be frequently lubricated and maintained properly.

    Plain Bearing:

    They have rubbing surfaces with lubricants between them .Friction factor depends on the material and construction. Stiffness is good. Life depends on application and also depends on lubrication


    Roller Bearing:

    Ball or rollers are used between rotating surfaces. This prevent and minimize the friction. Life is moderate and speed changes according to requirements. These kind of bearings are widely used now a days.

    01-roller bearing-thrust roller bearing-roller ball bearing

    Jewel bearing:

    Jewel bearing has an off centre bearing rolls in seating. Friction of this bearings is very low.  Speed and life are low.

    01-jewel bearings-plastic bearings

    Fluid Bearing:

    In these bearings fluid is forced between two faces and held in by edge seal. Friction is zero at zero speed. Stiffness is very high. Can be used for high speed applications. Life is infinite in some applications.

    01-fluid bearings-fluid circulative bearings-liquid bearings

    Magnetic Bearing:

    The two faces of bearing are kept separate by magnets. Zero friction at zero speed but eddy currents are often induced. Stiffness is low and there is no practical limit for speed and life.

    01-magnetic bearing-magnetic levitation bearings

    fag active magnetic bearing, magnetlager

    Flexure Bearing:

    These bearings are provided with material flexes to give any constrain movement. Friction is very low. Stiffness is low, and speed can be very high with high life.

    01-flexure bearing-air bearing-frictionless bearing

    Reducing friction in bearings is commonly important for efficiency. It helps to cutback the wear and tear and to facilitate extended use at high speeds and to avoid heating and premature failure of the bearing. Friction of a control depends on its form, material, and fluid used between two surfaces applied on bearings. Completely different bearing operative have different operational speed limits. Plain bearings generally handle only lower speeds. However the gap between the components that are separated by the bearing varies with load. Forces working on the bearing may be radial, axial or bending moments perpendicular to the most axis.