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७1003 Pages: 3

couplings?

Distinguish between rigid and flexible coupling

A rectangular sunk key 14 mm wide, 10 mm thick and 75 mm long is required
to transmit 1200 N-m torque from a 50 mm diameter solid shaft. Determine
whether the length is sufficient or not if the permissible shear stress and
crushing stress are limited to 56 MPa and 168 MPa respectively.

What is critical speed of a shaft?

Explain shock and fatigue factor.

Design a shaft to transmit power from an electric motor to a lathe head stock
through a pulley by means of a belt drive. The pulley weighs 200 N and is
located at 300 mm from the centre of the bearing. The diameter of the pulley is
200 mm and the maximum power transmitted is 1 kW at 120 rpm. The angle of
lap of the belt is 180° and the coefficient of friction between the belt and pulley
is 0.3. The shock and fatigue factors for bending and twisting are 1.5 and 2.0.

The allowable shear stress in the shaft may be taken as 35 MPa.

मैप मर KR

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