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Power Transmission devices

Power Transmission devices. Syllabus (ME-101-F). Section-A Introduction to machine tools Basic Concepts of thermodynamics Properties of steam & steam generators Section-B Refrigeration & Air conditioning. Hydraulic turbines & pumps. Section-C Power transmission methods & devices

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Power Transmission devices

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  1. Power Transmission devices For more info. : www.goodwisher.com

  2. Syllabus(ME-101-F) • Section-A • Introduction to machine tools • Basic Concepts of thermodynamics • Properties of steam & steam generators • Section-B • Refrigeration & Air conditioning. • Hydraulic turbines & pumps. • Section-C • Power transmission methods & devices • Stresses & strains • Section-D • Introduction to manufacturing system(NC & CNC Machining) For more info. : www.goodwisher.com

  3. Topics • Introduction to Power transmission, • Belt& Rope DRIVE • Chain • Gear drive. • Types and functioning of clutches. For more info. : www.goodwisher.com

  4. Power transmission devices • The devices, which are used to transmit power from one shaft to another For more info. : www.goodwisher.com

  5. Types of power transmission devices • Belts & rope drives:They are used where the distance between the axes of two shafts to be connected is considerable • Chain drives: They are used, where the distance between the shaft centers is short . • Gears:They are used for transmitting motion & power,when the distance between the shafts is relatively small. • Clutches:They are used for power transmission between the coaxial shafts. For more info. : www.goodwisher.com

  6. Belts & Rope Drives • The transmission of power in factories from one rotating shaft to another that lies at a considerable distance is achieved through belt & rope drives. • The shafts are fitted with pulleys, the belt is wrapped around the pulley & its ends are connected to form an endless connector • The belt & pulleys remain in contact by the frictional grip. For more info. : www.goodwisher.com

  7. Types of belted system • Open belted system. • Closed belted system. For more info. : www.goodwisher.com

  8. Open belted system Slack side Pulley B(Follower) Tension side Pulley A(driver) For more info. : www.goodwisher.com

  9. Open system(Contd…) • Pulley A, which is connected to a rotating shaft is called DRIVER. • Pulley B, that needs to be driven is termed as follower or driven. • When the driver rotates, it carries the belt because of friction that exists between the pulley & belt, the frictional resistance develops all along the contact surfaces, that makes the belts carry the follower which too starts rotating. For more info. : www.goodwisher.com

  10. Closed system Pulley B(Follower) Pulley A(driver) For more info. : www.goodwisher.com

  11. Closed belted system(Contd…) • Pulley A, which is connected to a rotating shaft is called DRIVER. • Pulley B, that needs to be driven is termed as follower or driven. • When the driver rotates, it carries the belt because of friction that exists between the pulley & belt, the frictional resistance develops all along the contact surfaces, that makes the belts carry the follower which too starts rotating. For more info. : www.goodwisher.com

  12. Types of belt drives • Flat belts • V-belts • Circular belts For more info. : www.goodwisher.com

  13. Belts FLAT BELT V- BELT CIRCULAR- BELT For more info. : www.goodwisher.com

  14. FLAT BELTS • IT has a narrow rectangular crossection. • The flat belts are easier to use and are subjected to minimum bending stress. • Material used is leather For more info. : www.goodwisher.com

  15. V-Belts • A v-belt is a trapezoidal section running on the pulleys with grooves cut to match the belt. • A V-belt is usually made up of cotton fabric or rubber which is vulcanised in moulds. • These are used in heavy duty machines For more info. : www.goodwisher.com

  16. Circular belts/Round belts • The round crossectionbelts are employed when low power is to be transmitted such as in instruments,house hold appliances,table top machine tools & machinery of clothing industry. For more info. : www.goodwisher.com

  17. Length of the open belted system: B B O2 O1 r1 x r2 For more info. : www.goodwisher.com

  18. Length of the open belted system:(Contd….) • Length of the belt is given by:- • L=2(arc EA + AB + arc BF) For more info. : www.goodwisher.com

  19. Length of the open belted system:(Contd….) • r1& r2 be the radius of the two pulleys. • X be the distance between O1& O2. • sin • As = • = For more info. : www.goodwisher.com

  20. Length of the open belted system(Contd….) • Arc EA= r1(+ • Arc BF= r2(-) • AB= • =[x2-(r1- r2)2]1/2 • x[1-]1/2 • =Applying bionomialtheoram: • AB=x{1-} For more info. : www.goodwisher.com

  21. Length of the open belted system(Contd….) • L=2(arc EA+AB+arc BF) • L=2[r1(++x{1-}+ r2 (-)] • 2[( r1 + r2 )+(r1- r2 )+x - ] • =( r1 + r2)+2(r1 - r2)+2x - • Putting the value of For more info. : www.goodwisher.com

  22. Length of the open belted system (Contd….) • ( r1 + r2 )+ 2(r1 - r2)+2x - • = • On putting the value: • ( r1 + r2 )+2x + For more info. : www.goodwisher.com

  23. R Ratio of tensions for flat belt R F=R F E B A T+T T T+T O T T1 T2 For more info. : www.goodwisher.com

  24. Ratio of tensions(Contd….) • Let T1 be the tension on tight side & T2 be the tension on the slacked side. • Considering the equilibrium of the forces in vertical direction: R=(T+T) sin ) + T sin () for be small sin () For more info. : www.goodwisher.com

  25. Ratio of tensions(Contd…) • R= (T+T) ) + T () • R=TT T T)is very small, so it can be neglected R=T+T=T R=T 1 For more info. : www.goodwisher.com

  26. Ratio of tensions(Contd….) • Considering the equillibrium of the forces in horizontal direction:- • R=(T+T) cos ) - T cos() • For to be small,cos 1 • R=(T+T) - T • R=T+T- T • R=T • R= 2 For more info. : www.goodwisher.com

  27. Ratio of tensions(Contd….) • From 1 & 2: • T= • = • Ln||= • = For more info. : www.goodwisher.com

  28. Ratio of tensions for V-Belt 2 For more info. : www.goodwisher.com

  29. Ratio of tensions for V-Belt(Contd…) • Let 2 be the angle of the groove. • N be the normal reaction between the belt & side of the V-Groove. • R be the total reaction in the plane of the groove. Considering the equillibrium between R & N:- R=Nsin + Nsin=2Nsin N= 1 For more info. : www.goodwisher.com

  30. Ratio of tensions for V-Belt(Contd…) • Total frictional resistance=N+N • =2N • From 1 put in 2: • Total frictional resistance= 2 For more info. : www.goodwisher.com

  31. R Ratio of tensions for V-Belt(Contd…) F=Rcosec T+T T For more info. : www.goodwisher.com

  32. Ratio of tensions for V-Belt(Contd…) • Considering the equilibrium of the forces in vertical direction: R= (T+T) sin ) + T sin () for be small sin () For more info. : www.goodwisher.com

  33. Ratio of tensions for V-Belt(Contd…) • R= (T+T) ) + T () • R=TT T T)is very small, so it can be neglected R=T+T=T R=T 1 For more info. : www.goodwisher.com

  34. Ratio of tensions for V-Belt(Contd…) • Considering the equillibrium of the forces in horizontal direction:- • RCosec=(T+T) cos ) - T cos() • For to be small,cos 1 • RCosec=(T+T) - T • RCosec=T+T- T • RCosec=T 2 For more info. : www.goodwisher.com

  35. Ratio of tensions for V-Belt(Contd…) • From 1 & 2:- • TCosec=T • Cosec= • Integrating both sides • = • Ln||= • = For more info. : www.goodwisher.com

  36. Chains drives • Chain drives are used where the distance between the shaft centers is short such as in cycles, motor vehicles, road rollers etc. • The chains are made up of rigid links which are hinged together . • The hinging provides flexibility needed for wrapping them around the driving & driven wheels. • The wheels (called sprockets)have projecting teethswhich fits into corresponding recess in the links of the chain. For more info. : www.goodwisher.com

  37. Chain drive For more info. : www.goodwisher.com

  38. Advantages of chain drives • No slip takes place & that ensures a perfect velocity ratio. • High transmission efficiency. • Chain drive takes less space than belt drives • A single chain can transmit motion to several shafts. • More suitable for transmitting the power when the distance between the shafts is less. For more info. : www.goodwisher.com

  39. Types of chain drives CHAIN DRIVES Hoisting & hauling chains Conveyor chains Power transmission chains Oval links Square links Silent chains Block chains Roller chains For more info. : www.goodwisher.com

  40. Hoisting & hauling chains • The links in such chains are of oval or square shape. • The joints of oval links are welded,the sprockets used for such chains have receptacles to receive the links. • These chains operate at low speed such as in anchors for marine work. • Chains with square links are used for hoists, cranes etc • They have low manufacturing cost. For more info. : www.goodwisher.com

  41. Hoisting & hauling chains For more info. : www.goodwisher.com

  42. Conveyor chains • The links in this chain is of either hook joint type or of closed joint type. • They are meant for continous conveying & elevating of the materials. • These chains run at average slow speed. For more info. : www.goodwisher.com

  43. Conveyor chains Hook joint type Closed joint type For more info. : www.goodwisher.com

  44. POWER TRANSMISSION CHAINS • AVAILABLE in BLOCK,ROLLER & SILENT configuration. • Block chains:-Belong to earliest stages of development in power transmission. • There occurs rubbing action between the teeths & links leading to a noisy operation. For more info. : www.goodwisher.com

  45. POWER TRANSMISSION CHAINS(Contd…) • Roller chains: Assembly consist of • Rollers link plate & pin link plate. • Pins, bushes & rollers. • ROLLERS ARE free to rotate on bush which is secured in a hole. The pin passes through the hole & roller is held by roller link plates • The central pins are joined and held in the position by pin link plates provided on both the sides. For more info. : www.goodwisher.com

  46. Power transmission chains(Silent chains ) • The inverted tooth silent chains have a series of flat laminations or links of peculiar V-Shape with an included angle 60 to 75. • These links have a direct contact with the sprocket wheel teeth. • The edges of the links are & corresponding faces of the links are quite straight & there occurs no relative motion between the links & wheel teeth. For more info. : www.goodwisher.com

  47. Gears & gear drives • Toothed wheel or gear is essentially a wheel with teeths cut on its periphery. • Power or motion is transmitted from one shaft to another with gear drive when: • Centre distance is relatively small. • High torque is to be transmitted. For more info. : www.goodwisher.com

  48. Gears For more info. : www.goodwisher.com

  49. Types of gear drives • Spur gear. • Helical gear. • Bevel gear. • Spiral gear. • Worm gear. • Rack and pinion gear. • Internal & external gear. For more info. : www.goodwisher.com

  50. Spur gear • It is a cylindrical gear whose tooth traces are straight lines parallel to gear axis. For more info. : www.goodwisher.com

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