Assignment 1

1. A leather belt 9mm x 250mm is used to drive a CI pulley 900mm in diameter at 336rpm. If the active arc on the smaller pulley is 120 o and stress in tight side is 2Mpa, find the power capacity of the belt. The density of the leather may be taken as 980 kg/m 3 and coefficient of friction of leather on CI is 0.35. [AUC-May 2007] 2. Design a FLAT belt drive to transmit 10 KW at 400 rpm. The speed ratio is 3. The distance between the pulley centres is 600 mm. the drive is for a crusher. [AUTDec2010] 3. Design a flat belt drive to transmit 10KW @1000rpm. The centre distance is 2m and the speed ratio is 3.

Assignment 2

1. Design a pair of straight SPUR gears to transmit 15 KW at 1440 rpm. Speed reduction is 3. State clearly all assumptions made. Check for compressive and bending stresses. Also check for plastic deformation of teeth. Tabulate the results neatly. [AUT-Dec2010] 2. Design a spur gear pair to transmit 5KW at 1440 rpm from an electric motor to an air compressor running at 720rpm. Take working life as 10,000 hrs. 3. Design a straight spur gear drive to transmit 8KW. The pinion speed is 720rpm and the speed ratio is 2. Both the gears are made of the same surface hardened carbon steel with 55RC and core hardness less than 350BHN. Ultimate strength is 720 N/mm 2 and yield strength is 360 N/mm 2 .

Assignment 3

A power of 20 KW is to be transmitted through a cone clutch at 500 rpm. For uniform wear condition find the main dimensions of the clutch and shaft. Also determine the axial force required to engage the clutch. Assume the coefficient of friction as 0.25, the maximum normal pressure on the friction surface is not to exceed 0.08 MPa and take the design stress for the shaft material as 40 MPa. A single block brake, the diameter of drum is 250mm and the angle of contact is 90 o . The operating force of 700N is applied at the end of lever which is at 250mm from the centre of the brake block. Determine the torque that may be transmitted. Fulcrum is at 200mm from the centre of brake block with an offset of 50mm from the surface of contact. The coefficient of friction is 0.35 A rope drum of an elevator having 650mm diameter is fitted with a brake drum of 1m diameter. The brake drum is provided with 4 cast iron brake shoes each subtending an angle of 45 o .The mass of elevator when loaded is 200Kg and moves with a speed of 2.5m/s. The brake has sufficient capacity to stop the elevator in 2.75m. Assuming the coefficient of friction as 0.2, find .