Pb-1A spring loaded safety valve for a boiler is required to blow off at a pressure of 1.3 N/mm2. The diameter of the valve is 95 mm. Design a suitable compression spring for this safety valve. Assuming spring index to be 8 and 25mm initial compression. Maximum lift of the valve is 20 mm. Shear stress is 450MPa. Take G=0.84X105MPa. [5M]
Pb-2A bronze spur pinion rotating at 400 rpm drives a cast iron spur gear at a transmission ratio of 4 : 1. The allowable static stress for both pinion and gear is 200 N/mm2. The pinion has 20 standard 20degree full depth involute teeth of module 20 mm. The face width of the gears is 50 mm. Find the power that can be transmitted from the point of strength. (Assume Cv=3/(3+v) ) [5M]