EXERCISES 1. A shaft running at 400 rp.m. transmits 10 kW. Assuming allowable shear stress in shaft as 40 MPa. find the diameter of the shaft. [Ans. 35 mm] 2. A hollow steel shaft transmits 600 kW at 500 rpm. The maximum shear stress is 62.4 MPa. Find the outside and inside diameter of the shaft, if the outer diameter is twice of inside diameter, assuming that the maximum torque is 20% greater than the mean torque. [Ans. 100 mm; 50 mm) 3. A hollow shaft for a rotary compressor is to be designed to transmit a maximum torque of 4750 N-m. The shear stress in the shaft is limited to 50 MPa. Determine the inside and outside diameters of the shaft, if the ratio of the inside to the outside diameter is 0.4. [Ans. 35 mm: 90 mm) 4. A motor cur shaft consists of a steel tube 30 mm internal diameter and 4 mm thick. The engine develops 10 kW at 2000 rp.m. Find the maximum shear stress in the tube when the power is transmit ted through a 4:1 gearing. [Ans. 30 MPa] 5. A cylindrical shaft made of steel of yield strength 700 MPa is subjected to static loads consisting of a bending moment of 10 kN-m and a torsional moment of 30 kN-m. Determine the diameter of the shaft using two different theories of failure and assuming a factor of safety of 2. [Ans. 100 mm] 6. A line shaft rotating at 200 rp.m. is to transmit 20 kW. The allowable shear stress for the material of the shaft is 42 MPa. If the shaft carries a central load of 900 N and is simply supported between bearing 3 metre apurt, determine the diameter of the shaft. The maximum tensile or compressive stress is not to exceed 56 MPa. [Ans. 50 mm) 7. Two 400 mm diameter pulleys are keyed to a simply supported shaft 500 mm apart. Each pulley is 100 mm from its support and has horizontal belts, tension ratio being 2.5. If the shear stress is to be limited to 80 MPa while transmitting 45 kW at 900 rp.m., find the shaft diameter if it is to be used for the input-output belts being on the same or opposite sides. [Ans. 40 mm) 8. A cast gear wheel is driven by a pinion and transmits 100 kW at 375 r.p.m. The gear has 200 machine cut teeth having 20 pressure angle and is mounted at the centre of a 0,4 m long shaft. The gear weighs 2000 N and its pitch circle diameter is 1.2 m. Design the gear shaft. Assume that the axes of the gear and pinion lie in the same horizontal plane. [Ans. 80 mm] 9. Fig. 14.17 shows a shaft from a hand-operated machine. The frictional torque in the journal bearings at A and B is 15 N-m each. Find the diameter (d) of the shaft (on which the pulley is mounted) using maximum distortion energy criterion. The shaft material is 40 C 8 steel for which the yield stress in tension is 380 MPa and the factor of safety is 1.5. (Ans. 20 mm]

EXERCISES 1. A shaft running at 400 rp.m. transmits 10 kW. Assuming allowable shear stress in shaft as 40 MPa. find the diameter of the shaft. [Ans. 35 mm] 2. A hollow steel shaft transmits 600 kW at 500 rpm. The maximum shear stress is 62.4 MPa. Find the outside and inside diameter of the shaft, if the outer diameter is twice of inside diameter, assuming that the maximum torque is 20% greater than the mean torque. [Ans. 100 mm; 50 mm) 3. A hollow shaft for a rotary compressor is to be designed to transmit a maximum torque of 4750 N-m. The shear stress in the shaft is limited to 50 MPa. Determine the inside and outside diameters of the shaft, if the ratio of the inside to the outside diameter is 0.4. [Ans. 35 mm: 90 mm) 4. A motor cur shaft consists of a steel tube 30 mm internal diameter and 4 mm thick. The engine develops 10 kW at 2000 rp.m. Find the maximum shear stress in the tube when the power is transmit ted through a 4:1 gearing. [Ans. 30 MPa] 5. A cylindrical shaft made of steel of yield strength 700 MPa is subjected to static loads consisting of a bending moment of 10 kN-m and a torsional moment of 30 kN-m. Determine the diameter of the shaft using two different theories of failure and assuming a factor of safety of 2. [Ans. 100 mm] 6. A line shaft rotating at 200 rp.m. is to transmit 20 kW. The allowable shear stress for the material of the shaft is 42 MPa. If the shaft carries a central load of 900 N and is simply supported between bearing 3 metre apurt, determine the diameter of the shaft. The maximum tensile or compressive stress is not to exceed 56 MPa. [Ans. 50 mm) 7. Two 400 mm diameter pulleys are keyed to a simply supported shaft 500 mm apart. Each pulley is 100 mm from its support and has horizontal belts, tension ratio being 2.5. If the shear stress is to be limited to 80 MPa while transmitting 45 kW at 900 rp.m., find the shaft diameter if it is to be used for the input-output belts being on the same or opposite sides. [Ans. 40 mm) 8. A cast gear wheel is driven by a pinion and transmits 100 kW at 375 r.p.m. The gear has 200 machine cut teeth having 20 pressure angle and is mounted at the centre of a 0,4 m long shaft. The gear weighs 2000 N and its pitch circle diameter is 1.2 m. Design the gear shaft. Assume that the axes of the gear and pinion lie in the same horizontal plane. [Ans. 80 mm] 9. Fig. 14.17 shows a shaft from a hand-operated machine. The frictional torque in the journal bearings at A and B is 15 N-m each. Find the diameter (d) of the shaft (on which the pulley is mounted) using maximum distortion energy criterion. The shaft material is 40 C 8 steel for which the yield stress in tension is 380 MPa and the factor of safety is 1.5. (Ans. 20 mm]

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

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