Q1. A single plate friction clutch with both sides effective is to be used to transmit 7kW at 720 rev/min. The outer diameter of the clutch plate is 600mm and the inner diameter is 180mm. The effective coefficient of friction is 0.4. The axial load for the clutch is provided by four springs each of stiffness 3kN/m. Calculate EACH of the following:
(a) The spring compression required when the clutch is new;
(b) The percentage reduction in the maximum power which can be transmitted if 3mm of Plate wear occurs.
Note: For constant pressure T = 2μnW(r13- r23 )/(3 (r12-r22 )
For constant pressure T = μnW(r1+ r1 )/2
Where n = Number of surfaces in contact.
Q1. A short column of solid circular section is to carry an axial compressive load.
(a) Determine, as a ratio of the diameter of the column, the greatest distance from the center line of the column that the line of action of the load can have without any part of the column being in tension.
(b) A 200mm diameter short solid column carries an axial compressive load of 400Kn placed at half the maximum eccentricity determined above. Calculate the greatest compressive stress in the column.
Q1. A compound bar consists of a round copper bar of 28mm diameter tightly encased in a steel tube 40mm diameter and of the same length. A tensile load of 100kN is applied. Calculate EACH of the following:
(a) The stress in the copper bar;
(b) The stress in the steel.
Note: For steel, Modulus of Elasticity = 210 GN/m2
For copper, Modulus of Elasticity = 90 GN/m2
Q1. A symmetrical I-shaped beam is shown in Fig. The beam is simply supported at both ends and carries a uniformly distributed load of 30kN per meter length and a single concentrated load of 6kN at mid-span. Calculate the maximum permissible length of the beam if the bending stress in the beam is not to exceed 140 MN/m2.
Q1. A vessel is to be re-engine and the shafting changed so that a 20 percent higher maximum power is transmitted at a 10 percent reduction in maximum speed. The original shaft was made of steel of UTS 500MN/m2 and was solid with a diameter of 450mm. The replacement shaft is to have the same outside diameter as the original but be made of steel of UTS 800MN/m2 and be hollow. The original safety coefficient (factor of safety) of eight is to be maintained for the replacement shaft.
Calculate EACH of the following:
(a) The maximum torque that the original shaft can transmit;
(b) The maximum permissible internal diameter of the replacement shaft.
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