Design of transmission systems qb
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Design of transmission systems qb Design of transmission systems qb Document Transcript

  • Question bank 6 sem MECH Anna university DESIGN OF TRANSMISSION SYSTEMS UNIT-1PART - A1. Name the four types of belts used for transmission of power.2. What is wiping? How it can be avoided in belt drive?3. What are the materials used for V grooved pulleys?4. When do you prefer a wire rope drive?5. Write any four wire rope applications.6. How are wire ropes designated?7. List out the various stresses induced in the wire ropes.8. While designing a wire rope drive, always, a larger sleeve diameter is preferred justify the statement?9. Give any three applications of chain drives?10. What is backsliding in chain drives?11 What is a V flat drive?12 What do you mean by galling of roller chain?13 What do you mean by chordal action of chain drive?14 What is an offset in a roller chain?15 What type of belt would you prefer if the center distance between the pulleys is small?16 Define creep and slip in belts.17 Give some application of wire ropes18 What do you understand by simplex, duplex and triplex chain?Part B11. (i) A V- belt drive is to transmit 15kW to a compressor. The motor runs at 1150 rpm and thecompressor is to run at 400 rpm. Determine.1. Belt specifications2.Number of belts (8)(ii) A leather belt 125mm wide and 6mm thick, transmit power from a pulley with the angle of lap 150and =0.3. If the mass of1m3 of leather is 1mg and the stress in the belt is not to exceed 2.75 Mpa, findthe maximum power that can be transmitted and the corresponding speed of the belt. (8)12. It is required to select a flat belt drive for a fan running at 360rpm.which is driven by a 10kw,1440rpm motor. The belt drive is open type and space available for a center distance of 2mapproximately. The diameter of a driven pulley is 1000mm. (16)13. Design a belt drive to transmit20kw at 720rpm aluminium rolling machine, the speed ratio being 3.The distance between the pulley is3m.diameter of rolling machine pulley is 1.2m. (16)14 A truck equipped with a 9.5 kw engine uses a roller chain as the final drive to the rear axle .Thedriving sprocket runs at 900 rpm and driven sprocket at 400rpm with center distance of approximately600mm.Select the roller chain. (16)15 A crane is lifting a load of 18 KN through a wire rope and a hook. The weight of the hook etc., is 10kN.The load is to be lifted with an acceleration of 1m/sec2. Calculate the diameter of the wire rope. Therope diameter may be taken as 30 times the diameter of the rope. Take a factor of safety of 6 andYoung’s modulus for the wire rope 0.8 x 105 N/mm2. The ultimate stress may be taken as 1800 N/mm2.The cross-sectional area of the wire rope may be taken as 0.38 times the square of the wire ropediameter. (16)16 Design a chain drive to actuate a compressor from 15kW electric motor running at 1,000 r.p.m, thecompressor speed being 350 rpm. The minimum centre distance is 500 mm. the compressor operates 15hours per day. The chain tension may be adjusted by shifting the motor (16)17 Design a chain drive to actuate a compressor from a 12 kW electric motor at 900 rpm, thecompressor begins 250 rpm. Minimum centre distance should be 500 mm, the chain tension may beadjusted by shifting the motor on rails. The compressor is to work 8 hour/day. (16)Powered by www.technoscriptz.com Page 1
  • Question bank 6 sem MECH Anna university18 A 15 kW squirrel cage motor, 1250 r.p.m. is driving a centrifugal pump at 550 r.p.m. The centrifugalpump is located at 700 mm form the motor. Design a chain drive. (16)19 A crane is lifting a load of 25 KN through a wire rope and a hook. The weight of the hook etc., is 15kN.The load is to be lifted with an acceleration of 1m/sec2. Design the rope drive. (16)20 Design a V-belt drive and calculate the actual belt tension and average stress for the following data.Driven pulley diameter, D= 500 mm, driver pulley diameter, d=150 mm, center distance c=925 mm,speed n1 = 1000 rpm, n2 = 300 rpm and power, P = 7.5 kW. (16) UNIT-2Part A1. What are the materials used for worm and worm gear?2. Define normal pitch of a worm gear?3. What is irreversibility in worm gears?4. Where do we use worm gears?5. Under what situation, worm gears are used?6. For bevel gears, define back cone distance?7. Under what situation, bevel gears are used?8. Differentiate a straight bevel gear and spiral bevel gear?9. What are the advantages of spiral bevel gears over straight bevel gears?10. What a is zero bevel gear?11 What is the difference between an angular gear and a miter gear?12 What are the applications of worm and worm gear?13 Why is the non ferrous material used for worm wheel?Part B11. A 10 kW motor running at 1200 rpm drives a compressor at 780 rpm through a 900 bevel gearingarrangement. The pinion has 30 teeth. The pressure angle of the teeth is 200. Both the pinion and gearare made of heat treated cast iron grade 35. Determine the cone distance, average module and facewidth of the gears. (16)12. Design a pair of bevel gears for two shafts whose axes are at right angles. The power transmitted is25kW. The speed of the pinion is 300 rpm and the gear is 120 rpm. (16)13. A 2 kW power is applied to a worm shaft at 720 rpm. The worm is of quadruple start with 50mm aspitch circle diameter. The worm is of quadruple start type with 50mm as pitch circle diameter. Theworm gear has 40 teeth with 5mm module. The pressure angle in the diametral plane is 200. Determine(i) the lead angle of the worm, (ii) velocity ratio, and (ii) centre distance. Also, calculate efficiency of theworm gear drive, and power lost in friction (16)14.A pair of straight tooth bevel gears has a velocity ratio of 4/3. The pitch diameter of the pinion is 150mm. The face width is 50mm. The pinion rotates at 240 rev/min. The teeth are 5mm module, 14 10involutes. If 6 kW is transmitted, determine (i) the tangential force at the Mean radius (ii) the pinionthrust force (iii) the gear thrust force. Draw the free body diagrams indicating the forces (16)15 Design a worm gear drive with a standard centre distance to transmit 7.5 kW from a warm rotating at1440 rpm to a warm wheel at 20 rpm (16)16 Design the teeth of a pair of bevel gears to transmit 18.75 kW at 600 rpm of thepinion. The velocityratio should be about 3 and the pinion should have about 20 teeth which are full depth 200 involutes.Find the module, face width, diameter of the gears and pitch core angle for both gears (16)17 A 900 degree straight bevel gear set is needed to give a 3:1 reduction. Determine the pitch coneangle, pitch diameter, and gear forces if the, 25 degree pressure angle pinion ahs 15 teeth of pitch circlediameter, 4, and the transmitted power is 8 HP at 550 pinion rpm (16)Powered by www.technoscriptz.com Page 2
  • Question bank 6 sem MECH Anna university18. Design a worm gear drive to transmit 22.5 kW at a worm speed of 1440 rpm. Velocity ratio is 24:1.An efficiency of at least 85% is desired. The temperature rise should be restricted to 400 C. Determinethe required cooling area (16)19 A speed reducer wait is to be designed for an input of 11.25kW with a transmission ratio of 20. Thespeed of the hardened steel worm is 1500 rpm. The worm wheel is to be made of bronze. The toothform is to be 200 in volute (16)20 Design a bevel gear drive to transmit 3.5 kW with the following specifications: speed ratio = 4; drivingshaft speed = 200 r.p.m.; drive is non-reversible; material for pinion is steel; material for wheel is castiron; and life 25000 hours (16) UNIT-3PART - APart A1. Write any two requirements of a speed gear box?2. Why G.P. series is selected for arranging the speeds in gear box?3. List any two methods used for changing speeds in gear box?4. What are preferred numbers?5. What is step ratio? Or Define progression ratio?6. What is kinematic arrangement, as applied to gear boxes?7. What does the ray-diagram of gear box indicate?8. State any three basic rules to be followed while designing a gear box?9. What are the possible arrangements to achier 12 speeds from a gear box?10. What is a speed reducer?11 What are the main applications of gear box?12 What are the main functions of gear box cover?13 List out the possible arrangement to achieve 16 speed gear box?Part B11. (i) The maximum and minimum speeds of a 6 speed gear box are to be 1600 rpm and 500 rpmrespectively. Construct the speed diagram and the kinematic arrangement of the gearbox. (8)(ii) Design a gearbox, for the following data:No of speeds required=16; min speed=100rpm; maxspeed=560rpm;Draw diagram and kinematic arrangement. (8)12. Design a 12 speed gearboxThe speed range required is 100 to 355rpma) Draw the ray diagram,b) Draw the kinematic arrangementc) Calculate the no. of teeth on each gear. (16)13. A gearbox is to give 18 speeds for a spindle of a milling machine. The drive is from an electric motorof 3.75kw at 1440rpm. Maximum and minimum speeds of the spindle are to be around 650rpm and35rpm respectively. Find the speed ratios which will give the desired speeds and draw the structuraldiagram and kinematic arrangement of the drive. (16)14.Design a nine speed gear box for a milling machine with speed ranging from 56-900rpm. The outputspeed is 720rpm; make a neat sketch of the gearbox. Indicate the no of teeth on all the gears and theirspeeds. (16)15.The min and max speeds of a six speed box are to be 160 and 1500rpm.Construct the kinematicarrangement and the ray diagram of the gearbox and also calculate the no of teeth of all gears (16)16 A gearbox is to be designed to provide 12 output speeds ranging from 160 to 200rpm. The inputspeed of motor is 1600rpm. Choosing a standard speed ratio construct the speed diagram and thekinematic arrangement calculate the no of teeth of all gears (16)Powered by www.technoscriptz.com Page 3
  • Question bank 6 sem MECH Anna university17 .A six speed gear box is required to provide output speeds in the range of 125 to 400 r.p.m. with astep ratio of 1.25 and transmit a power of 5 kW at 710 r.p.m. Draw the speed diagram and kinematicsdiagram. Determine the number of teeth module and face width of all gears, assuming suitablematerials for the gears. Determine the length of the gear box along the axis of the gear shaft. (16)18. A machine tool gear box is to have 9 speeds. The gear box is driven by an electric motor whose sh aftrotational speed is 1400 r.p.m. The gear box is connected to the motor by a belt drive. The maximumand minimum speeds required at the gear box output are 1000 r.p.m. and 200 r.p.m. respectively.Suitable speed reduction can also be provided in the belt drive. What is the step ratio and what are thevalues of 9 speeds? Sketch the arrangement. Obtain the number of teeth on each gear and also theactual output speeds. (16) 19. Design a 9 speed gear box for a machine to provide speeds ranging from 200 r.p.m to 1000 rpm. Theinput is from a motor of 5 kW at 1440 rpm. Assume any alloy steel for the gear.(16)20. In a milling machine, 18 different speeds in the range of 35 rpm and 650 rpm are required. Design athree stage gear box with a standard step ratio. Sketch the layout of the gear box, indicating the numberof teeth n each gear. The gear box receives 3.6 kW from an electric motor running at 1,440 rpm. Sketchalso the speed diagram. (16) UNIT-4PART - A1. How do you classify the cams?2. What are the disadvantages of knife-edge follower?3. What are the different types of follower motions?4. What is the function of a clutch?5. Give examples for axial and radial friction clutch?6. What are the properties required of the material used as a friction surface?7. Name few commonly used friction materials?8. Clutches are usually designed on the basic of uniform wear, why?9. Distinguish between dry and wet operation of clutches?10. In case clutch semi-cone angle should be greater than 12˚ why?11 What is the difference between cone and centrifugal clutches?12 Compare disc clutches and cone clutches?13 Given the reaction to find temperature rise in clutches?14 What is the friction of a brake?15 Differentiate a brake and a clutch?16 What is a self locking brake?17 What do you mean by self energizing brakes?Part B11. A single plate clutch , both side being effective is required to connect a machine shaft to a drivershaft which runs at 500rpm .The moment of inertia of the rotating parts of the machine is 1Kgm2.Theinner and the outer radii of the friction discs are 50mm&100mm respectively .Assuming uniformpressure of 0.1N/mm2 and µ =0.25 , determine the time taken for the machine to reach full speed whenthe clutch is suddenly engaged . Also determine the power transmitted by the clutch, the energydissipated during the clutch slip and the energy supplied to the machine during engagement. (16)12. A multi – disk clutch consists of five steel plates and four bronze plates. The inner and outerdiameters of friction disks are 75mm and 150mm respectively. The coefficient of friction is 0.1 and theintensity of pressure is limited to 0.3 N/mm2. Assuming the uniform wear theory, calculate (i) therequired operating force, and (ii) power transmitting capacity at 750 rpm.(16)Powered by www.technoscriptz.com Page 4
  • Question bank 6 sem MECH Anna university14. In an automotive type internal – expanding double – shoe brake he face width of the friction lining is40 mm and the intensity of normal pressure is limited to 1 N/mm2 . The coefficient of friction is 0.32.The angle φ1 can be assumed to be zero. Calculate (i) the actuating force P, and (ii) the torque –absorbing capacity of the brake. (16)15.A leather faced conical clutch has cone angle of 300.The pressure between the contact surfaces islimited to .35N/mm2 and the breath of the conical surface is not to exceed 1/3 of the mean radius. Findthe dimensions of the contact surface to transmit 22Kw at 2000 rpm .Also calculate the force required toengage the clutch. .Take µ =0.15 . (16)16.Draw the displace time , velocity time and the acceleration time curves for the follower in order tosatisfy the following conditions(1) Stroke of the follower 25mm(2) Outstroke takes place with SHM during 900 of cam rotation(3) Return stroke takes with SHM during 750 of cam rotation(4) Cam rotates with a uniform speed of 800 rpm (16)17.A radial cam rotates at 1200 rpm with the follower rising 20mm with SHM in1500of the cam rotation.The roller is 32mm in diameter and the prime circle is 80mm in diameter. Check whether undercuttingwill occur. (16)18.A multi – disk clutch has 3 disks on the driving shaft and two on the driven shaft. The inne r and outerdiameters of friction disks are 120mm and 240mm respectively. The coefficients of friction is 0.3 andfind the max axial intensity of pressure between the discs for transmitting 25 kW at 1575 rpm .Assumingthe uniform wear theory. (16)19.A single plate clutch transmits 25 kW at 900 rpm. The max. Pressure intensity between the plates is85 kN/m2¬. The ratio of radii is 1.25. Both the sides of the plate are effective and the coefficient offriction is .25. Determine (i) the dia of the plate (ii) the axial force to engage the clutch. Assuming theuniform wear theory. (16)20. (i) What is a self energizing brake? When a brake becomes self-locking?.Discuss (8) (ii) What is positive clutch? Describe the types. (8)21.In a band and block brake, the band is lined with 14 blocks, each of which subtends an angle of20degrees at the drum centre. One end of band is attached to the function of the brake lever and theother to a pin 150mm from the fulcrum. Find the force required at the end of the lever 1 m l ong fromthe fulcrum to give a torque of 4kN-m. The diameter of the brake drum is 1m and the co-efficient offriction between the blocks and the drum is 0.25. (16) UNIT-5PART - A1. Define module?2. What are the advantages of toothed gears over the types of transmission system?3. In a pair of spur gears, the module is 6mm. Determine the circular pitch and the diametral pitch?4. What are the standard interchangeable tooth profiles?5. Why is pinion made harder than gear?6. What are the main types of gear tooth failure?7. What are the assumptions made in deriving lewis equation?8. When do you use non-metallic gears?9. Define pitch circle with reference to spur gears?10. What are the common forms of fear tooth profile?11 Define transmission ratio with reference to spur gears?12 Back lash for spur gears depends on which two factors?13 What are the non metallics’s used as gears?Powered by www.technoscriptz.com Page 5
  • Question bank 6 sem MECH Anna university14 When do you prefer helical gears than spur gears?15 What is the major disadvantage of single helical gear? How can you over come that difficulty?16 What hands of helix are used in parallel helical gears?17 Define axial pitch of a helical gear?18 Why is the crossed helical gear drive mostly not used for power transmission?19 What is Herringbone gear? State its application.20 Where do we use skew gears?Part B11. (i) A pinion with 25 teeth and rotating at 1200rpm drives a gear which rotates at 200rpm and moduleis 4mm.calculate the center distance between the gears. (8)(ii) A helical gear with 300 helix angle has to transmit 35kW at 1500 rpm. With a speed reduction ratio2.5. If the pinion has 24 teeth, determine the necessary module for 200 full depths the teeth. Assume15Ni 2Cr 1 Mo 15 material for both pinion and wheel. (8)12. Design a spur gear drive required to transmit 45 Kw at pinion speed of 800 rpm. The velocity ratio3.5:1. The teeth are 20 full depths involute with 18 teeth on the pinion. Both the pinion gear are madeof steel with a maximum safe static stress of 180N / mm2 ¬ (16)13. Design a pair of helical gears to transmit 30kW power at a speed reduction ratio of 4:1. The inputshaft rotates at 2000 rpm. Take helix and pressure angles equal to 250 and 200 respectively. Thenumber of teeth on the pinion may be taken as 30 (16)14 Design a straight spur gear drive to transmit 8 kW. The pinion speed is 720 rpm and the speed ratio is2. Both the gears are made of the same surface hardened carbon steel with 55RC and core hardness lessthan 350 BHN. Ultimate strength is 720 N/mm2 and yield strength is 360 N/ mm2(16)15 A motor shaft rotating at 1500 rpm has to transmit 15kW to a low speed shaft with a speed reductionof 3:1. Assume starting torque to be 25% higher than the running torque. The teeth are 200 involuteswith 25 teeth on the pinion. Both the pinion and gear are made of C45 steel. Design a spur gear drive tosuit the above conditions and check for compressive and bending stresses and plastic deformations. Alsosketch the spur gear drive. (16)16 An electric motor is to be connected to a reciprocating pump through a gear pair. The gears areoverhanging in their shafts. Motor speed = 1440 rpm. Speed reduction ratio = 5. Motor power = 36.8kW. The gears are to have 200 pressure angles. Design a spur gear drive. (16)17 A pair of helical gears subjected to moderate shock loading is to transmit 37.5kW at 1750 r.p.m. ofthe pinion. The speed reduction ratio is 4.25 and the helix angle is 150. The service is continuous and theteeth are 200 FD in the normal plane. Design the gears, assuming a life of 10,000 hours. (16)18.A compressor running at 300 rpm is driven by a15 Kw, 1200 rpm motor through a 14½ 0 full depthspur gears .The centre distance is 375 mm .The motor pinion is to be of C30 forged steel hardened andtempered, and the driven gear is to be of cast iron. Assuming medium shock condition, design the geardrive. (16)19.Design a spur gear drive required to transmit 15 Kw at pinion speed of 1400 rpm to a low speed shaftrotating at 500 rpm. The teeth are 20 degree full depth involute with 25 teeth on the pinion. Both thepinion and gear are made of CI with a maximum safe static stress of 56 N / mm2. (16)20.A helical gear drive with the helix angle of 30 degree required to transmit 15 Kw at pinion speed of10000 rpm. The velocity ratio 4:1. The teeth are 20 degree full depth involute with 25 teeth on thepinion. Both the pinion gear is made of hardened steel with a maximum safe static stress of 100N /mm2. The face width may be taken as 14 times the module. Find the module and face width. (16)Powered by www.technoscriptz.com Page 6