Engineeringdev

Introduction to Automobile Engg. & Chassis Construction Chassis: 1. Chassis - A French term 2. It is a complete vehicle except the body 3. It is skeleton of the vehicle 4. Whole vehicle excluding the additional fitment Line diagram of Chassis:   Body: 1. Super structure of the vehicle 2. Cover to the chassis 3. Bolted to the vehicle 4. Made of pressed steel panels Power plant :   1. Also called as Engine 2. Provides necessary power to run the automobile Classification of Engines: 1. Petrol Engine 2. Diesel Engine

Comparator A comparator works on the relative measurement It gives only dimensional differences in relation to a basic dimension A comparator has to compare the unknown dimensions of a part with some standard (Basic Size) These are commonly used for linear measurement in mass production Classification Depending on the amplification system, Comparators are classified as Mechanical Comparators Electrical Comparators Optical Comparators Pneumatic Comparators

Mechanical Comparators : Mechanical comparator s are extremely convenient to use It does not require any external power for its operation The measuring head consists of the work contact plunger(Stylus) The movement due to size difference between standard and work piece operates a pointer The pointer moves over a dial This movement of the plunger is magnified by means of the gear train or levers The magnification of mechanical comparators is limited to 1000 These are cheap and intended to measure external surfaces However the mechanical devices are subjected to wear Types of Mechanical Comparators Dial indicator Reed type mechanical comparator The Sigma comparator

Comparator A comparator works on the relative measurement It gives only dimensional differences in relation to a basic dimension A comparator has to compare the unknown dimensions of a part with some standard (Basic Size) These are commonly used for linear measurement in mass production Classification Depending on the amplification system, Comparators are classified as Mechanical Comparators Electrical Comparators Optical Comparators Pneumatic Comparators

METROLOGY Metrology is the science of measurements. In manufacturing industry the dimensions are measured to control the shape and sizes of an object Controlled measurements are necessary in the manufacture of interchangeable parts Linear Measuring Instruments Slip gauges Dial indicator Angle Measuring Instruments Bevel Protractor Sine bar Angle gauge Slip gauges Slip gauges are used for precise measurement of parts and for verifying measuring tools such as micrometers,comparators and various limit gauges Slip gauges are rectangular blocks made of alloy steel having a cross-section of about 32mm by 9mm The distance between two opposite faces determines the size of the gauge During use, the required number of gauge blocks are used together to know the required dimension. Dial Indicators Dial indicators are used to test and inspect the size and trueness of a finished work It is measured to an accuracy of 0.01mm They are also used in conjunction with other measuring instruments like

Reed type Mechanical Comparator The instrument used to measure linear displacement of spindle with the help of the reed mechanism is known as reed type Mechanical comparator. It is a device magnifying small motions of spindle. Constructional details : The reed mechanism is frictionless device for magnifying small motions of the spindle It consists of a fixed block `A` which is rigidly fastened to the gauge head case The floating block `B` carries the gauging spindle The floating block is also connected horizontally to the fixed block by reeds `C` A vertical reed is attached to each block with upper ends jointed together These vertical reeds are shown in fig by letter `D` A pointer is attached to this joint Working principle A linear motion of the spindle moves the floating block vertically upwards This vertical movement causing the vertical reed on the floating block to slide past the vertical reed on the fixed block The movement causes both reeds swing through an arc As the point is

BOND ENERGY Definition : ·       The energy required to break a bond between the two bonded atoms is called bond energy. Or ·       The energy required to convert one mole of a diatomic molecular substance in the gaseous state into its free atoms is known as bond energy.  ·       As the bond energy increases, the stability of the bond also increases. ·       sigma - bonds are stronger than pi bonds ·       Number of bonds between atoms increases the overall bond strength increases -C-C- < -C=C- < -CC- BOND LENGTH AND ENGERY BOND LENGTH Definition: The distance between the centres of the nuclei of two covalently bonded atoms is known as bond length. ·       Bond lengths are measured in angstroms or nanometers.   METALLIC BOND ·       Properties of Metals: 1.       Metals are good electrical and thermal conductors 2.       They are opaque and have high refracting power 3.       They have high melting and boiling points 4.       They crystallise with high coordination number