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Posted by graham on November 17, 2003 at 13:20:21:
I was hoping somebody could come up with some answers and written out solutions for me for a couple questions I got on a recent exam i wrote.
1) A bevel gear drive is used to lift a sluice gat which has a mass of 3.055 tonnes. It is subject to a pressure of 276 kPa over its 2.4 metre diameter. The vertical screw spindel has a square thread of mean diameter of 75mm and a 25 mm pitch and passes through a bush fixed to a spindel. The coefficient of friction between the sluice and verticle guide on which it presses and between the screw and bush is equal to 0.1
The bevel wheen keyed to a spindle has 40 teeth and drive pinion on motor shaft has 10 teeth. Determine the Torque on motor shaft required to raise the gat neglecting losses, other than friction at the thread and sluice gate.
2)A mass of 336 kilograms falls through a distance of 17.5 mm on to the stop at the lower end of a vertical steel bar which is 5.2 metres long and 735 square mm in cross section area. If modulus of elasticity is equal to 210 GPascals for the bar.
Find: a)instantaneous elongation
b)The Stress in the bar.