Dom - 1st Mid - 3rd B.tech [2009]

DOM - 1st MID Questions - 3rd B.tech [2009] 1. (a) Derive an expression for gyroscopic couple? (b) An aeroplane makes a complete half circle of 60m radius to the left when flying at 200KM/hr.the rotary engine and the propeller of aeroplane weigh 4000N.with a radius of gyration 30cm.The engine runs at 2500rpm clockwise when viewed from rear end determine gyroscopic couple on aircraft and state its effect. 2. The ratio of connecting rod length to crank length for a vertical petrol engine is 4:11 The bore and stroke is 80mm&100mm respectively. The mass of reciprocating parts is 1KG and gas pressure on piston is 0.7n/mm2 when it has moved 10 mm from TDC on its power stroke determine net load on gudgeon pin when engine runs at 1800rpm and at what speed of engine this load will be zero. 3. the total mass of four wheeled trolley car is 3600kg.the car runs on rails of 1.6m apart and rounds a curve of 24m radius at 48km/hr.Track is banked at 120. the external diameter of wheel is 800mm and each pair with axle has a mass of 240kg with radius of gyration of 300mm.The height of the center of mass of car above the wheel base is 1000mm.determine the pressure on each rail allowing for centrifugal force and gyroscopic couple actions. 4. (a) What do you mean by friction circle? Explain? (b) A load of 10KN is raised by means of screw jack having a threaded screw of 12mm pitch and of diameter 50mm. if a force of 100N is applied at end of lever to raise the load. What should be the length of lever to be used? What should be the mechanical advantage obtained. state whether screw is self locking? Take coefficient of friction as 0.15. 5. (a) State laws of kinematic friction. (b) a conical pivot supports a load of 20KN, cone angle is not to exceed 0.3N/mm2. The external diameter is twice the internal diameter. If the shaft rotates at 200rpmand coefficient of friction is 0.1 determine 1) Outer & inner radius of bearing surface. 2) Determine power observed in friction considering uniform pressure and uniform wear. 6. In a thrust bearing the external diameter and the internal diameter of contact surfaces are 400MM & 250MM. the total axial load is 100KN &intensity of pressure is 300kn/mm2 shaft rotates at450rpm and coefficient of friction is 0.059. determine a) power lost in over coming friction b) determine number of collars required

7. a)Derive an expression for toque transmitting capacity of cone clutch by considering uniform pressure theory. b)a cone clutch is to be designed to transmit a power of 45kw at 1000rpm.The mean diameter and semi cone angle is 500mm and 12.5 0 . coefficient of friction is 0.2.Normal pressure on clutch is not to exceed 0.1N/MM determine 1)axial spring force to engage the clutch 2)the face width required 8. A single block brake is shown in figure the diameter of drum is 250mm and the angle of contact is 120 degrees. If the operating force of 900N is applied at the end of a lever and the coefficient of friction between the drum and the lining is 0.45 determine the torque that may be transmitted by the block brake.

9. (a)Derive expression for total breaking torque about fulcrum in simple band brake if the break drum is rotating in anti clockwise direction (b) Describe with neat sketch pronybreak dynamometer. 10. A horizontal steam engine 20cm in diameter by 40cm stroke ,connecting rod of 100cm makes 160rpm The mass of reciprocating parts is 50kg.when crank is turned through an angle of 300. the steam pressure is 4.5bar calculate (a) turning moment of crank shaft (b) if mean resisting torque is 30NM & mass of flywheel is 50KG and radius of gyration is 70CM. Calculate acceleration of fly wheel 11. a) State how the size of flywheel calculated. b)An oil engine working on 4-stroke cycle has a poer of 30kw itt’s speed 300rpm and fluctuation of speed is +/- 3% of wheel.The ratio of W.D during power stroke to the workdone during compression stroke is 2.5 assuming that workdone during suction stroke and exhaust strokes are negligible and assuming constant resistance i) Determine energy stored by the flywheel ii) moment of inetia of flywheel

12. The turning moment diagram for a multicylinder engine has been drawn to a vertical scale of 1mm=250N-m and horizontal scale of 1mm=3 º the areas above and below the mean torque line are -28, +380, -260, +310, -300, +242,-380, +265 and -229 sq.mm.The fluctuation of speed is limited to +/- 1.5% of mean speed which is 600rpm i) Determine the moment of inertia of flywheel ii) Determine the dimensions of rectangular fly wheel lib if the width is twice its thickness,The density of flywheel material is 7,250 kg/m³ and its hop space is 6mpa.Assuming that the ring contributes 95% of flywheel effect.