WEAR Wear is the removal of material from the component due to friction or contact with other component. It is necessary to measure the wear of a part because excessive wear may cause the failure of the component and accident may take place.
MEASUREMENT OF WEAR The parts having wear is measure by different gauges. Internal wear of a component is measure by depth gauge. External wear of any part can be measure by height gauges.
MEASUREMENT OF WEAR The wear between two surfaces which are very close to each other, can be measured by slip gauges as shown in fig. The wear of cylindrical part is measured by bore gauges.
MEASUREMENT OF NOISE Noise is any unpleasant sound such as booming, buzzing, whistling. While driving or in idle position if there is some undesirable noise of vehicle component, it should be checked. This noise is due to undesirable contact with other part or vibration. Hence we need to check these noises so we can avoid damage of vehicle component. 8
MEASUREMENT OF NOISE To check the noise we use “Db Meter”. Decibel Meter is designed for situations where small size, simple operation and high performance are all required. It allows noise levels to be checked quickly and simply with the large LCD digital display showing Sound Level in decibels. 9
MEASUREMENT OF NOISE FOR THE TRAFFIC NOISE MEASUREMENT AND ENGINE NOISE MEASUREMENT, THIS METER IS USED. 10
MEASUREMENT OF FUEL CONSUMPTION There are various mainly two types of measurements Automatic means using electronics. Manually
MEASUREMENT OF VIBRATION Vibration meter is used to measure the vibration of particular component. The result is shown in the form of digits in display. Reasons: high tolerance mis-alignment Shocks produced due to sudden change in acceleration. 16
MEASUREMENTS OF SPEED EDDY CURRENT TACHOMETER TACHOGENERATOR STROBOSCOPE PULSE COUNTER
EDDY CURRENT TACHOMETER Shaft whose rpm to be measured is made to drive a U-shaped magnet. This magnet rotates inside the soft-iron casing. An aluminum cup is placed between these two, so field magnet pass through the aluminum. With the relative rotation of magnet with respect to cup, eddy current is generated.
EDDY CURRENT TACHOMETER This eddy current generates its own magnetic field. This magnetic field attracts the field of rotating magnet (earlier field). As a result of it the cup tend to be carried round by a magnetic torque. This torque is proportional to the eddy current, hence in turn proportional to speed of magnet.
EDDY CURRENT TACHOMETER The cup is carried by spindle which is free to rotate through part of revolution. The pointer indicates the speed of on the dial of the instrument means dial. Speedometer works on this principle.
TACHOGENERATOR Here the armature of the dynamo rotates in the alnico of permanent magnetic field. Its electrical output is the signal of rpm. It is connected to a voltmeter graduated In rpm or km per hour.
PULSE COUNTER Three main parts are required- A 60 toothed mild steel wheel. A magnetic transducer. A pulse counter. The geared wheel which contains the equally spaced 60 slots is mounted on a shaft. Now here magnetic transducer is a bar magnet and has a coil of a wire wound around it.
PULSE COUNTER The ends of the coil are connected to the signal i/p of the pulse generator. As a tooth on a wheel approaches the end of bar magnet, the steel of the tooth provides an easier path for the magnetic field than the gap between the teeth did. Due to this flux density of field increases. Hence generation of voltage occurs.
PULSE COUNTER So, frequency of AC voltage = no of teeth passing through it With the help of magnetic transducer the ac o/p is collected by the pulse counter ckt (timer ckt ). The rpm of the rotating shaft is then displayed in the form of digital o/p.