Handouts
LINK: Flexible Machine Elements
Topics:
Flat Belts
V-Belts
Timing Belts
Ribbed Belts
CVT Belts
Chains and Sprockets
Exercises
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1. A pulley has an effective belt pull of 4 kN and an angle of belt contact of 160 deg. The working stress of belt is 1.8 MPa. Find the thickness of belt to be used if the width is 320 mm and coefficient of friction is 0.30. a. 13.54 mm b. 12.24 mm c. 15.21 mm d. 10.11 mm 2. A compressor is driven by 25 kW motor by means of V-belt. The service factor for moderate shock load of 1.30 and the adjusted horsepower capacity of V-belt are 5 hp. Determine the number of belts required. a. 8 b. 9 c. 10 d. 11 3. A 3/8-in flat belt is 12-in wide and is used in 28-in diameter pulley rotating at 700 rpm. The specific weight of belt is 0.038 lb/in3. The angle of contact is 160 deg. If coefficient of friction is 0.32 and stress is 380 psi, how much power can it deliver? b. 120 hp c. 110 hp d. 150 hp 4. Determine the belt length of an open belt to connect the 8 cm and 14 cm diameter pulley at a center distance of 50 cm. a. 137 cm b. 140 cm c. 118 cm d. 153 cm 5. Find the angle of contact on the small pulley for a belt drive with center distance of 75-in. If pulley diameters are 9-in and 18-in, respectively. a. 173 deg b. 162 deg c. 155 deg d. 184 deg A nylon-core flat belt has an elastomer envelop 200 mm wide and transmits 70 kW at a belt speed of 30 m/s. The belt is used in a crossed configuration to connect a 280 mm diameter driving pulley to a 910 mm diameter driven pulley at a shaft spacing of 5 m. 6. Calculate the belt length and the angles of wrap. a. 11.40 m, 155 deg b. 16.25 m, 164 deg c. 10.25 m, 140 deg d. 11.94 m, 194 deg 7. Compute the belt tensions based on a coefficient of friction of 0.35. a. 4.66 N and 2.88 N b. 2.81 N and 0.25 N c. 3.28 N and 0.85 N d. 3.36 N and 1.03 N A pulley 615 mm in diameter transmits 40 kW at 630 rpm. The arc of contact between the belt and pulley is 140 deg, the coefficient of friction between the belt and pulley is 0.30, and the safe working stress of the belt is 2.0 MPa. Calculate: 8. The effective belt pull a. 1.2 kN b. 1.1 kN d. 1.5 kN 9. The width of the belt used if its thickness is 7 mm. a. 230 mm b. 290 mm d. 210 mm 10. A pulley has a belt pull of 3.0 kN. If 30 HP motor is used to drive the pulley, compute the belt speed, in ft/s. a. 20.5 b. 24.5 c. 33.7 d. 15.6 11. A pulley has an effective belt pull of 4 kN and an angle of belt contact of 160 deg. The working stress of the belt is 2.1 MPa. Find the thickness of the belt to be used if the width is 400 mm and the coefficient of friction is 0.30. a. 8.4 mm b. 6.3 mm c. 10.5 mm d. 5.8 mm 12. A pulley 580 mm in diameter transmits 60 kW at 650 rpm by means of belt. Determine the effective belt pull. a. 1.32 kN b. 6.82 kN c. 5.22 kN d. 3.04 kN 13. A belt connected pulleys has 12 cm diameter and 35 cm diameter. If the center distance is 60 cm, find the angle of contact of the smaller pulley. a. 165 deg b. 158 deg c. 142 deg d. 133 deg 14. The torque transmitted in a belt connected 310 mm diameter pulley is 5 kN-m. Find the power driving the pulley if belt speed is 25 m/s. a. 532.1 kW b. 644.2 kW c. 806.5 kW d. 332.1 kW 15. A 10 cm pulley turning at 650 rpm is driving a 24 cm pulley by means of belt. If the total belt slip is 6%, find the speed of the driving gear. a. 253.8 rpm b. 265.1 rpm c. 200.0 rpm d. 281.3 rpm 16. Determine the belt length of an open belt to connect the 5 cm and 10 cm diameter pulley at a center distance of 75 cm. a. 155 cm b. 143 cm c. 174 cm d. 188 cm 17. Find the angle of contact on the small pulley for a belt drive with center distance of 73-in if pulley diameters are 7-in and 14-in, respectively. a. 188 deg b. 143 deg c. 155 deg d. 174 deg 18. A 3-strand chain and sprocket turns 650 rpm and has a service factor of 1.5. If 15 HP/strand chain is to be used, find the torque that the chain and sprocket can deliver. a. 242.4 ft-lb b. 265.1 ft-lb c. 205.3 ft-lb d. 212.8 ft-lb 19. A pump operates on a head of 35 m, delivering 80 L/s of water at 80% efficiency. The pump is driven by a diesel engine by means of a chain and sprocket with a service factor of 1.4. If the horsepower per strand is 28, find the approximate number of strands needed. a. 1 b. 2 d. 4 20. A certain farm equipment which requires 2500 N-m torque at 600 rpm has diesel engine to operate at 1600 rpm as its prime mover. A No.60 roller chain with total length of 60 pitches and small sprocket of 24 teeth are to be used with operating temperature to remain constant at 40 deg C. Determine the number of teeth of larger sprocket. a. 60 b. 56 c. 64 d. 68 21. A driving sprocket with 12 teeth drives another sprocket with 48 teeth by means of a chain having a pitch of 3/4-in. If chain length is 75-in, find the center distance between sprockets. a. 25.9 in b. 32.6 in c. 20.6 in d. 38.5 in 22. A sprocket with 9.0-in diameter and pitch of 3/4-in drives another sprocket at standard center distance of 50 pitches. Find the diameter of larger sprocket. a. 33 in b. 25 in c. 38 in d. 20 in 23. A 20-teeth sprocket driving a 100 teeth sprocket a center distance of 38 pitches. Find the chain length, in pitches. a. 110 b. 140 c. 120 d. 100 24. Find the standard distance between sprocket having 6-in and 18-in diameters. a. 21 in b. 18 in c. 28 in d. 32 in 25. A chain with speed of 900 fpm has driving sprocket turns at 1000 rpm. If the pitch of chain is 3/4-in, find the number of teeth of driving sprocket. a. 12 b. 14 c. 16 d. 18 26. A 20-teeth driving sprocket that rotates at 700 rpm and pitch chain of 1/2-in drives another sprocket at a speed of 200 rpm. Find the diameter of the driven sprocket. a. 8 in b. 9 in d. 10 in 27. A fan requires at least 6 HP to deliver 19,000 CFM of air running at 350 rpm. For a service factor of 1.20, find the designed horsepower of the sprocket. a. 8.3 b. 11.1 c. 5.3 d. 7.2 28. A chain and sprocket has a pitch diameter of 30-in and with 90 teeth available. Find the pitch of the chain. a. 4 in b. 3 in c. 2 in d. 1 in 29. A chain and sprocket has a pitch diameter of 9.56-in and pitch of 1/2-in. How many teeth are there in the sprocket? a. 32 b. 48 c. 58 d. 60 30. A chain and sprocket has 24 teeth with chain pitch of 3/4-in. If the sprocket turns 620 rpm, find the speed of the chain. a. 13.3 ft/s b. 12.5 ft/s c. 18.9 ft/s d. 15.5 ft/s 31. A chain and sprocket has 20 teeth with chain pitch of 3/4-in. Find the pitch diameter of sprocket. a. 3.2 in b. 6.4 in c. 5.7 in d. 4.8 in |
Flat Belts
An open belt drive connects a 450 mm driving pulley to another driven pulley 1000 mm in diameter. The belt is 300 mm wide and 10 mm thick. The coefficient of friction of the belt is drive is 0.3 and the mass of the belt is 2.8 kilograms per meter of belt length. Other data are: Center distance between shaft = 4m; Maximum allowable tensile stress on the belt = 1500 kPa; Speed of driving pulley = 900 rpm. Determine the maximum power that can be transmitted in kilowatts.
SOLUTION:
