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2016 SUMMER

State any four advantages of ball bearings over plain journal bearings.

1) The ball bearings have a far smaller contact area and thus have a lower frictional drag coefficient. 2) Due to less frictional drag means better response and less power consumption. 3) The turbo can spool up much faster, which reduces turbo-lag and offers a major performance advantage over journal bearing turbochargers at lower to mid turbocharger speeds. 4) The reduced contact area of the ball bearings means that it requires far less lubrication, allowing for lower oil pressure feeds. 5) The ball bearing more reliable. 6) Less expensive.

State any six design considerations while designing the spur gear

1) The power to be transmitted 2) The velocity ration or speed of gear drive. 3) The central distance between the two shafts 4) Input speed of the driving gear. 5) Wear characteristics of the gear tooth for a long satisfactory life. 6) The use of space & material should be economical. 7) Efficiency & speed ratio 8) Cost

Describe the importance of aesthetic considerations in design related to shape, colour and surface finish.

1) The shape should not be like blocks but various forms like sculpture, streamlined, aerodynamic, taper should be used. 2) The component should be symmetrical at lean about one axis. 3)proper shape of a product help to make the product more attractive. 4) The shape of the product should be regular, even & proportionate Regarding Colour: ……….Any 2 pt : 1 M Each 1) The colour and shape of component should be such that in should attract appeal and impress customer. 2) The colour should match with conventions, moods e.g.

State any four advantages and disadvantages of welded joints over riveted joints.

1. The welded structures are usually lighter than riveted structures. This is due to the reason, that in welding, gussets or other connecting components are not used. 2. The welded joints provide maximum efficiency (may be 100%) which is not possible in case of riveted joints. 3. Alterations and additions can be easily made in the existing structures. 4. As the welded structure is smooth in appearance, therefore it looks pleasing. 5. In welded connections, the tension members are not weakened as in the case of riveted joints. 6. A welded joint has a great strength.

State any four applications of spring.

1) To cushion, absorb or control energy to external load : Car springs, Railway buffers 2) To store Energy : Watches Toys 3) To Measure forces : Spring Balances, Gauges ,Engines 4) To provide clamping force in Jigs & fixtures. 5) To apply forces as in brakes, clutches & spring loaded valve.

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