Q8 Machine Design TE1134 b) 1 KW power at 720 rpm is supplied to worm shaft, worm gearing system is Designated as 4/30/10/5. Normal pressure angle is 20. Calculate: 1. Coefficient Friction 2. Efficiency of worm gear drive 3. Power lost in friction 6 Q5 Design a pair of helical gears to transmit 30 kW power at a speed reduction of 4:1. The 20 input shaft rotates at 2000rpm. Take helix angle as 25 and normal pressure angle as 20. Both the pinion and the gear are made of steel with permissible stress of 220 MPa and core hardness of 300 BHN. The number of teeth on the pinion may be taken as 30. Q6 a) Prove that the efficiency of ACME thread for lifting the load is given by: tana (1-.sec.tana) (u. sece+tana) Where, 'u'is coefficient of friction, 'a' is lead angle, '0' is semi-thread angle. b) Design a connecting rod for a high-speed IC engine using the following data: 5 15 Cylinder bore = 125 mm Length of connecting rod = 300 mm Maximum gas pressure = 3.5 MPa Length of stroke = 125 mm Engine speed = 2200 rpm Mass of reciprocating parts = 1.6 kg F9282 Assume suitable data and state the assumptions you make. Part-C a) Design a screw jack for lifting a load of 100 kN through a height of 50 cm. Take 16 the following material for the components of screw jack: 1 Screw 2 Nut 3 Handle C30 Phosphor Bronze Syt-Syc-400MPA Sut=190MPa Syt=400MPa Q7 Assume factor of safety = C30 5 as the failure of screw jack may result in serious consequences. Also, check the screw for buckling. b) List the advantages of Cast Iron piston over aluminium piston 4 a) Derive the Stribeck's equation for the static load carrying capacity of a rolling 7 contact bearing. b) Prove and explain as why I-section is ideally suitable for connecting rod. c) For a single plate clutch, derive the relationship for torque transmitting capacity in terms of coefficient of friction, diameter of clutch and operating force using uniform pressure theory. 7 6 3 CADA