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mounted at D, 250 mm to the left of the bearing B. The gear is driven by a
pinion with a downward tangential force while the pulley drives a horizontal belt
having 180° wrap angle. The pulley also serves as flywheel and weighs 2 KN.
The maximum belt tension is 3.5 kN and the tension ratio is 3:1. Take the yield
stress for the material as 380 MPa and factor of safety as 2.

What do you mean by critical speed of a shaft?

Design a rectangular sunk key made of steel for a 90 mm diameter mild steel
shaft to transmit a torque of 150 Nm. Assume shear stress -50 MPa and crushing
stress= 120 MPa.

Two helical springs of the same axial length but different diameters of coil are
coaxially placed one inside the other. The axial load is 5 kN and the deflection is
32 mm. The maximum permissible shear stress in both the springs is 150MPa.
The spring indices are 5 and 9. The wire diameters are being same, neglecting
the effect of stress concentration; find the wire diameters and ratio of actual
number of coils of the two springs.

Design a flange coupling which connects a motor and a pump shaft made of
steel. The flange and hub of the assembly are made of cast iron having shear
strength 14 MPa. The power transmitted is 3 kW at a shaft speed of 960 rpm.
Take the permissible shear stress and crushing stress for steel used as 50 MPa
and 90 MPa respectively.

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