ANNA UNIVERSITY CHENNAI
REGULATION 2013
ME6503-DESIGN OF MACHINE ELEMENTS
UNIVERSITY QUESTIONS Click: DME Unit 1 Question Bank
Click: DME Unit 5 Question Bank
UNIT-2 TWO MARKS
1. On what basis are shafts designed?
2. What are the effects of introducing keyways in shafts?
3. What is the use of register in a flange coupling?
4. How is the strength of a shaft affected by the Keyway?
5. What are the various stresses induced in the shafts?
6. Name any two of the rigid coupling.
7. A shaft of 70mm long is subjected to shear of 40 MPa and has an angle of twist equal to 0.017 radian.Determine the diameter of the shaft. Take G = 80 GPa.
8. What is the main use of woodruff keys?
9. Why a hollow shaft has greater strength and stiffness than solid shaft of equal weight?
10. Under what circumstances flexible couplings are used?
11. What are the various stresses induced in the shafts?
12. Name the two of the rigid coupling.
13. What is the difference between rigid and flexible coupling?
14. Classify keys with its applications.
15. Write the advantages of the knuckle joints.
16. State Castiglione's theorem.
Click: DME Unit 5 Question Bank
16 MARKS
1. A hollow transmission shaft having inside diameter 0.6times the outside diameter is made of plain carbon steel 40C8 and the factor of safety is 3. A belt pulley, 1000mm in diameter, is mounted on the shaft which overhangs the left hand bearing by 250mm.The belts are vertical and transmit power to the machine shaft below is 3kN and 1 kN respectively, while the weight of the pulley is 500N. The angle of wrap of the belt on the pulley is 180o. Calculate the outside and inside diameter of the shaft.
2. The layout of a shaft carrying two pulleys 1 and 2, and supported on two bearings A and B is shown in figure. The shaft transmits 7.5 k W power at 360 rpm from pulley 1 to pulley 2. The diameters of pulley 1 and 2 are 250 mm and 500 mm respectively. The masses of pulley 1 and 2 are 10 and 30 kg respectively. The belt tensions act vertically downward and ratio of belt tensions on the tight side to slack side for each pulley are 2.5:1. The shaft is made of plain carbon steel 40 C8 (Syt) = 380 N / mm2) and the factor of safety is 3. Estimate suitable diameter of shaft. If the permissible angel of twist is 0.5° per meter length, calculate the shaft diameter on the basis of tensional rigidity. Assume G = 79300 N / mm2
3. A steel solid shaft transmitting 15 kW at 200 rpm is supported on two bearings 750 mm apart and has two gears keyed to it. The pinion having 30 teethes of 5mm module is located 100mm to the left of the right hand bearings and delivers power horizontally to the right. The gear having 100 teeths of 5 mm module is located 150 mm to the right of the left hand bearing and receives power in a vertical direction from below. Using an allowable stress of 54 MPa in shear. Determine the diameter of the shaft.
4. A steel solid shaft transmitting 15 kW at 200 rpm is supported on two bearings 750 mm apart and has two gears keyed to it. The pinion having 30 teeths of 5mm module is located 100mm to the left of the right hand bearings and delivers power horizontally to the right. The gear having 100 teeths of 5 mm module is located 150 mm to the right of the left hand bearing and receives power in a vertical direction from below. Using an allowable stress of 54 MPa in shear. Determine the diameter of the shaft.
5. A horizontal nickel steel shaft rests on two bearings, A at the left and B at the right end and carrier two gears C and D located at distance of 250 mm and 400 mm respectively from the centre line of the left and right bearings. The pitch diameter of the gear C is 600 mm and that of gear D is 200 mm. The distance between the centre line of the bearing is 2400 mm. The shaft transmits 20kW at 120 rpm. The power is delivered to the shaft at gear C and is taken out at gear D in such a manner that the tooth pressure Ftc of the gear C and Ftd of the gear D act vertically downwards.
6. Find the diameter of the shaft, if the working stress is 100MPa in tension and 56 MPa in shear. The gear C and D weights 950 N and 350 N respectively. The combined shock and fatigue factors for bending and torsion maybe taken as 1.5 and 1.2 respectively.
7. A hollow shaft for a rotary compressor is to be designed to transmit a maximum torque of 3500 N-m. The shear stress in the shaft is limited to 50Mpa.Determine inside and outside diameter of the shaft, if the ratio of inside and outside diameter is 0.4.
8. A hoisting drum 0.5 m in diameter is keyed to a shaft which is supported in two bearings and driven through a 12:1 reduction ratio by an electric motor. Determine the power of the driving motor, if the maximum load of 8 kN is hoisted at a speed of 50 m/min and the efficiency of the drive is 80%. Also determine the torque on the drum shaft and the speed of the motor in rpm. Determine also the diameter of the shaft made of machinery steel, the working stresses of which are 155 MPa in tension and 50 MPa in shear. The drive gear whose diameter is 450 mm is mounted at the end of the shaft such that it overhangs the nearest bearing by 150 mm . The combined shock and fatigue for bending and torsion may be taken as 2 and 1.5 respectively
9. A rigid type of coupling is used to connect two shafts transmitting 15kW at 200 rpm. The shaft keys and bolts are made of C45 steel and the coupling is cast iron. Design the coupling.
10. A turbine shaft transmits 500kw at 900 rpm. The permissible shear stress is 80 N/mm^2 while twist is limited to 0.5 degree in a length of 2.5 m. calculate the diameter of the shaft. take G=0.8 *105 N/mm2. if the shaft chosen as hollow with d3/d03 = 0.6. Calculate the percentage of saving in material.
11. Determine the dimension of flange coupling that connects a motor and a pump shaft. The power to be transmitted a 2 kW at a shaft speed of 960 rpm. Select suitable materials for the parts of the coupling and list the dimensions.
12. Design a muff coupling to connect two steel shafts transmitting 25 kW power at 360 rpm. The shafts and key are made of plain carbon steel 30C8.The sleeve is made of grey cast iron FG 200.The factor of safety is the shaft and key is 4.Foe example the sleeve ,the factor of safety is 6 based ultimate strength.
13. Determine the dimension of flange coupling that connects a motor and the pump shaft. The power to be transmitted a 2kW at a shaft speed 960 rpm. Select suitable materials for the parts of the coupling and the dimensions.
14. A hoisting drum 0.5 m in diameter is keyed to a shaft which is supported in two bearings and driven through a 12:1 reduction ratio by an electric motor. Determine the power of the driving motor, if the maximum load of 8 kN is hoisted at a speed of 50 m/min and the efficiency of the drive is 80%. Also determine the torque on the drum shaft and the speed of the motor in rpm. Determine also the diameter of the shaft made of machinery steel, the working stresses of which are 155 MPa in tension and 50 MPa in shear. The drive gear whose diameter is 450 mm is mounted at the end of the shaft such that it overhangs the nearest bearing by 150 mm. The combined shock and fatigue for bending and torsion may be taken as 2 and 1.5 respectively
15. Design a bushed-pin type of flexible coupling to connect a pump shaft to a motor shaft transmitting 32kW at 960 rpm. The overall torque is 20% more than mean torque. The material properties are as follows:
(i) The allowable shear and crushing stress for shaft and key material is 40 MPa and 8-MPa respectively.(ii) The allowable shear stress for cast iron is 15 MPa(iii) The allowable bearing pressure for rubber is 0.8 N/mm2(iv) The material of the pin is same as that of shafts and key.Draw neat sketch of the coupling.
16. Design a protective type flange coupling to connect two shafts to transmit 15kW at 600 rpm.
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