CHENDU COLLEGE OF ENGINEERING & TECHNOLOGY DEPARTMENT OF MECHANICAL ENGINEERING QUESTION BANK IV SEMESTER

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1 CHENDU COLLEGE OF ENGINEERING & TECHNOLOGY DEPARTMENT OF MECHANICAL ENGINEERING QUESTION BANK IV SEMESTER Sub Code: ME 6401 KINEMATICS OF MACHINERY UNIT-I PART-A 1. Sketch and define Transmission angle of a four-bar mechanism. What are the worst values of transmission angle? 2. What is the condition for correct steering of an automobile? 3. Write Grashoff s law for 4-bar mechanism. 4. What is meant by indexing mechanism? Where do we use it? 5. What is Kutzbach criterion for planar mechanism? 6. Sketch an exact straight line mechanism, with link proportions. 7. Give any two inversions of a single slider chain. 8. What is meant by Kinematic Pair? 9. State the difference between mechanism and structure. 10. Differentiate the machine and structure. 11. Classify the constrained motion. 12. Define sliding connectors. 13. Differentiate rotation and translation. 14. What is meant by Ackermann steering? 15. Write down the Grashof s Law for a four bar mechanism? 16. Explain the working principle of bicycle bells. 17. What is meant by motion adjustment mechanism? 18. Whether a cycle chain is kinematic chain or not? 19. Define instantaneous centre. 20. What is instantaneous axis? 21. What is resistant body? 22. What is link? 23. What are the different types of links? 24. What is meant by spatial mechanism? 25. What is the use of oldham s coupling? PART B 1. Explain the working of two different types of quick return mechanisms. Derive an expression for the ratio of time taken in forward and return stroke for one of these mechanisms. (16) 2. Sketch and explain any three kinematic inversion of four bar chain. 3. (i)what is kinematic inversion? Explain the four different inversions of slider crank mechanism. (10) (ii) Determine the degree of freedom for following linkages. (6) 4. (i) Find the maximum and minimum transmission angles for the mechanisms shown in The figures indicate the dimensions in standard units of length. (8) (ii) Write short notes on toggle mechanism. (8) 5. Explain the inversions of four bar chain with examples.

2 6. Sketch and explain the following: ( i ) Elliptical trammel (8) ( ii) Scotch yoke mechanism. (8) 7. Sketch and explain the four inversions of Single-slider crank chain. (16) 8. (i) What are straight-line mechanisms? Sketch the Peaucellier straight-line motion mechanism and prove that the generating point moves in straight line. (8) (ii)sketch a Hooke's joint and derive the condition for equal speeds of driving and driven shafts. (8) 9. (i) Explain Kutzbach criterion for the mobility of a mechanism with suitable example. (4) Dimensions are in cm M1, M2, M3 and M4 are four-bar linkages as shown in figure. The numbers on the figure indicate the respective link lengths in cm. Identify the nature of the mechanism, i.e. whether double crank, crank rocker or double rocker. Give reasons in brief. (4 x 3 = 12) 10. (i) Explain, with a neat sketch, how an offset slider crank mechanism can be used as a quick-return motion mechanism. Derive an expression to find the quick-return ratio. (10) (ii) With a suitable diagram, explain how a pantograph works. What are its uses? (6) 11. Explain the working a quick return motion mechanism. Also derive an equation for the ratio of time taken for return stroke and forward strokes. 12. Explain the working of a toggle mechanism and its application with a neat sketch. 13. (i) Explain the inversions of four bar chain, with neat sketches. (8) (ii) Explain with neat sketches the following : (8) Offset slider mechanism. An indexing mechanism. 14. (i) Explain the inversions of single slider crank chains, with neat sketches. (10) (ii) Explain mechanical advantage and transmission angle related to Four- bar mechanisms. (6) 15. What is degree of freedom of a mechanism? How is it determined? Define Grashof s law. State how is it helpful in classifying the four link mechanisms into different types? Find the maximum and minimum transmission angles for the mechanisms shown in Fig. The figures indicate the dimensions in standard units of length. UNIT II PART A 1. What is a configuration diagram? What is its use? 2. Define rubbing velocity in a pin joint and write the equation for calculating the same. 3. What is a configuration diagram? What is its use?

3 4. Define rubbing velocity. What will be the expression for rubbing velocity at a pin joint when the two links rotate in opposite direction? 5. Illustrate the instantaneous centers of a typical four bar mechanism. 6. State the condition for a link to experience coriolis acceleration. 7. Draw an acceleration polygon for a crank rotating at an angular speed of ' co' rad/sec and angular acceleration of 'a' rad/sec2. 8. Explain how the direction of Coriolis acceleration is obtained. 9. Write about rubbing velocity. 10. Write down the expression for finding the number of instantaneous centres in a mechanism. 11. Define instantaneous centre. 12.What is the expression for coriolis component of acceleration? 13. Define number of instantaneous centre. 14. What is low degree of complexity? 15. What is centrode? 16. What is space centrode? 17. What is Body centrode? 18. What is Instantaneous axis? 19. What is axode? 20. Write down the different types of Instantaneous centres. 21. Define Kennedy s theorem. 22. What are properties of instantaneous centre? 23. What is angular velocity ratio theorem? 24. Explain any two methods of reducing interference in gears. 25. What is the effects of centrifugal tension in belt drives? PART B 1. (i) Derive an expression for the relationship between the angular velocities of links in terms of known link lengths, angular positions of links and angular velocity of input link, for a four bar linkage. (6) (ii) In a slider crank mechanism, the length of crank OB and connecting rod AB are 125 mm and 500 mm respectively. The centre of gravity G of the connecting rod is 275 mm from the slider A. The crank speed is 600 rpm clockwise. When the crank has turned 45 from the inner dead centre position, determine velocity of the slider A, Velocity of the point G and Angular velocity of the connecting rod AB (10) 2. By analytical method, Derive the velocity and acceleration for the reciprocating steam engine mechanism. 3. (i) The crank AB of four bar mechanism shown in figure. 3. Rotates at 60 rpm clockwise. Determine the relative angular velocities of the coupler to the crank and the lever to the coupler. Find also the rubbing velocities al the surface of pins 25 mm radius and the joints B and C. (8) (ii) Locate the instantaneous centre's of the slider crank mechanism shown in fig.4. Find the velocity of the slider. (8)

4 4. (i) Fig.5 shows the configuration of a whit worth quick return mechanism. The lengths of the fixed link OA and the crank OP are 200 mm and 300mm respectively. Other lengths are AR=200 mm and RS=400 mm. Find the velocity of the ram using instantaneous. centre method when the crank makes a angle of 120 with the fixed link and rotates at 10 rad/s. Fig. 5 Differentiate low degree and high degree of complexity with suitable sketch. 5. The following data refer to the dimensions of the links of a four-bar mechanism: AB = 50 mm; BC = 66 mm; CD = 56 mm and AD (fixed link) = 100 mm. At the instant when L DAB = 60, the link AB has an angular velocity of 10.5 rad/s in the counter clockwise direction. Determine the velocity of point C, velocity of point E on the link BC while BE = 40 mm and the angular velocities of the links BC and CD. Also sketch the mechanism and indicate the data. 6. A single slider-crank mechanism is shown in Fig. 12 b. Determine the acceleration at B & E and the angular acceleration of the link AB. The crank rotates at 20 rad/s counter-clockwise. Fig. 12 (b) 7. In a four bar chain ABCD, AD is fixed and is 120 mm long. The crank AB is 30 mm long and rotates at 100 rpm clockwise while the link CD = 60 mm oscillates about D; BC = 120 mm. Using graphical method, find the angular velocity and angular acceleration of link BC when angle BAD = 60. (16) 8. Derive the expressions for the velocity and acceleration of the piston of a reciprocating engine mechanism. (8) In a reciprocating engine mechanism, the lengths of the crank and connecting rod are 150 mm and 600 mm respectively. The crank position is 60 from inner dead centre. The crank shaft speed is 450 r.p.m. (clockwise). Using analytical method, determine 1) velocity of the piston (2) 2) Acceleration of the piston (2) 3) Crank angle for maximum velocity of the piston and the corresponding velocity. (4) 9. A four bar chain is represented by a quadrilateral ABCD in which AD is fixed and is 0.6 m long. The crank AB = 0.3 m long rotates in a clockwise direction at 10 rad/s and with an angular acceleration of 30 rad/s2,

5 both clockwise. The crank drives the link CD (= 0.36 m) by means of the connecting link BC (= 0.36 m). The angle BAD = 60. Using graphical method, determine the angular velocities and angular accelerations of CD and BC. (16) 10. A four-bar mechanism, with 02A as the input link, is shown in figure. i. Using analytical method, derive the equations for the angular velocity of the output link and of the connecting link AB. (8) ii. If the coordinates of the pin joints are 02 (0,0), A (-15, 26), B(75, 70) and 04(50, 0) and the input link rotates at 2 rad/s counter-clockwise, find the angular velocities of AB and of 04B. (8) 11. A slider crank mechanism has a crank of 30 mm length and connecting rod 50 mm length. The angular velocity of crank is 10 rad/sec(ccw). The angular acceleration of the crank is 1200 rad/sec2. The crank makes an angle of with the line of strike. Determine the acceleration of slider and angular acceleration of connecting rod. 12. The driving crank AB of a quick-return mechanism shown below revolves at a uniform speed of 200 rpm. Find the velocity of the tool-box R, in the position shown in Fig.1, when the crank makes as angle of 60 with the vertical line AP. Also determine the angular velocity of link PQ. 13. In the mechanism shown in Fig the crank OA rotates at a constant speed equal to 20 rpm anticlockwise and gives motion to the sliding blocks B and D. The dimensions of various links are OA = 300 mm; AB = 1200 mm; BC = 450 mm and CD = 450 mm. For the given configuration, determine : i. Velocities of sliders B and D ii. Angular velocity of link CD iii. Linear acceleration of D and iv. Angular acceleration of CD

6 14. For the Four-bar linkage shown in Fig. 12(b) find the acceleration of A and B and the angular acceleration of links 3 and 4, Crank 2 has a constant angular velocity, w2 = 200 radls counter clockwise direction. The linkage A0 2 = 150 mm; BA = 450 mm, B0 4 =300 mm, = 200 mm. 15. The Crank of a slider crank mechanisms rotates clockwise at a Constant speed of 600 r.p.m. The crank is 125 mm and connecting rod is 500 mm long. Determine 1. Linear velocity and acceleration of the mid Point of the connecting rod, and 2. Angular velocity and angular acceleration of the connecting rod, at a crank angle of 45 from inner dead centre position. (16) UNIT- III PART A 1. Which type of can follower motion is used in high speed engines? Why? 2. Why large pressure angle is not preferred in cam curves? 3. State the expressions for maximum acceleration of a follower moving with cycloidal motion. 4. Why sometimes the axes of translating roller followers in cam follower mechanisms are offset from the axis of rotation of cam? 5. What are the advantages of roller follower than knife-edge follower? 6. Sketch the displacement, velocity and acceleration diagram when a follower moves with uniform velocity. 7. What is the significance of pressure angle in cam? 8. What is the follower motion used for high speed cams? Why? 9. What are the major types of cams? 10. Define Angle of dwell. 11. Define tangent cam. 12. What are the different motions of the follower? 13. Define pressure angle. 14. Write the procedure to draw the cam profile. 15. What do you know about gravity cam? 16. Write the different types of follower. 17. What is cam profile? 18. What is base circle? 19. What is trace point? 20. What is pitch curve? 21. What is prime circle?

7 22. What is pressure angle? 23. What is pitch point? 24. What is pitch circle? 25. What is cam angle? PART B 1. A cam is designed for a knife edge follower with following data: Cam lift = 40 mm during 90 of cam rotation with SHM Dwell for the next 30 During the next 60 of cam rotation, the follower returns to original position with SHM Dwell for the remaining 180 Draw the profile of the cam when the line of stroke is offset 20 mm from the axis of the cam shaft. 2. In a cam with translating roller follower, the follower axis is offset to the right of Cam hinge by 12 mm. The roller radius is 10 mm and the cam rotates in the counter clock wise direction. Layout the rise portion of the cam profile to meet the following specifications: Rise takes place during 180 of cam rotation of which for the first 90 the rise is with constant acceleration and the rest is with constant retardation. Take seven station points only. The lift of the cam is 30 Earn and the least radius of the cam is 25 mm. 3. A cam operates on offset roller follower. The least radius of the cam is 50 mm, roller, diameter is 30 mm, and offset is 20 mm, the cam rotates at 360 rpm. The angle of ascent is 48, angle of dwell is 42, and angle of descent is 60. The motion is to be SHM during ascent and uniform acceleration and deceleration during decent. Draw the cam profile. (16) 4. (i) A flat faced mushroom follower is operated by a symmetrical cam with circular arc flank and nose profile the axis of tappet passed through the cam axis. Total angle of action is 162, lift 10 mm and base circle diameter 40 mm. period of acceleration is half the period of retardation during the lift. The cam rotates at 1200 rpm. Determine ( 1 ) The nose and flank radii and ( 2 ) The maximum acceleration and retardation during lift. (12) (ii) List the various methods to be used to reduce the pressure angle. (4) 5. A cam with a minimum radius of 25 mm, rotating clockwise at uniform speed of 300 rpm is to he designed to give motion to a flat faced mushroom follower as detailed below: i. To raise through a distance of 25 mm in 120 rotation of the cam ii. To remain at rest for the next 30 iii. To lower during further 120 rotation of the cam iv. To remain in the same position during rest of the revolution. The raising of the follower takes place with cycloidal motion and the lowering with uniform acceleration and retardation. However, the uniform acceleration is 2/3rd of the uniform retardation. Draw the displacement diagram and profile of the cam. 6. A circular cam operating a flat faced follower has a least diameter of 40 mm. The lift is 12mm and angle of action is 160. The Speed of rotation is 500 rpm. If the period of acceleration of the follower is 60% of the retardation during the lift, determine the following:, ( i ) The principal dimensions of the cam ( ii) The acceleration at the main points. Also determine the maximum acceleration and deceleration during the lift. 7. A cam with a minimum radius of 25 mm, rotating clockwise at a uniform speed is to be designed to give motion to a roller follower, at the end of a valve rod, as described below: To raise the valve through 50 mm during 120 rotation of the cam. To keep the valve fully raised through next 30. To lower the valve during next 60 and To keep the valve closed during rest of the revolution. The diameter of the roller is 20 mm and the diameter of the cam shaft is 25 mm. The line of the stroke is offset by 15 mm from the axis of the cam shaft. The displacement of the valve, while being raised and lowered is to take place with SHM. i. Draw the displacement diagram. Sketch roughly the shapes of velocity and acceleration diagrams. (6) ii. Draw the profile of the cam. (10)

8 8. In a symmetrical tangent cam operating a roller follower, the least radius of the cam is 30 mm and roller radius is 17.5 mm. The angle of ascent is 75 and the total lift is 17.5 mm. The speed of the cam shaft is 600 rpm. Assume that there is no dwell between ascent and descent. I. Calculate the principal dimensions of the cam. (6) II. Find the acceleration of the follower at the beginning of the lift. (2) III. Draw the profile of the cam. (8) 9. A cam is to be designed for a knife edged follower with the following data: I. Follower lift is 40 mm with SHM, during 90 of cam rotation II. Dwell for the next 30 III. IV. Follower return to its original position with SHM, during next 60 of cam rotation Dwell for the remaining cam rotation. The line of stroke of the follower passes through the axis of the cam Shaft. Radius of the base circle of the cam is 40 mm. 1. Draw the displacement diagram. (4) 2. Draw the profile of the cam. (8) 3. Determine the maximum velocity and acceleration of the follower during forward and return strokes, if the cam rotates at 200 rpm in CW direction. (4) 10. The following particulars relate to a symmetrical circular cam operating a flat faced follower : Least radius= 25 mm, Nose radius = 8 mm, Lift of the valve = 10 mm, Angle of action of cam = 120, Cam shaft speed = 1000 r.p.m. I. Find the flank radius. (4) II. Determine the maximum values of velocity, acceleration and retardation of the follower. (3) III. Draw the profile of the cam. (9) 11. A cam is to designed for a knife edge follower with the following data : cam lift = 40 mm during 90 of cam rotation with SHM, dwell for the next 30, during the next 60 of cam rotation, the follower returns to its original position with SHM, dwell during the remaining 180. Draw the profile of the cam when the line of stroke is offset 20 mm from the axis of the cam shaft. The radius of the base circle of the cam is 40 mm. 12. Draw a cam profile for operating the exhaust valve of an oil engine. It is required to give equal uniform acceleration and retardation during opening and closing of the valve each of which corresponds to 60 of cam rotation. The valve must remain in the fully open position for 20 of cam rotation. The valve is 37.5 mm and the least radius of the cam is 40 mm. The follower is provided with a roller of radius 20 mm and its line of stroke passes through the axis of the cam. 13. The following data are for a disc cam mechanism with roller follower : Minimum radius of the cam = 35 mm, lift of the follower = 40 mm Offset of the follower = 10 mm right, Roller diameter = 15 mm Cam rotation angles are as mentioned below : During ascent = 120, Dwell = 80 During descent = 80, Dwell = 80 Cam rotates in clockwise direction and the follower motion is simple harmonic during both ascent and descent. Draw the displacement diagram of the follower and indicate the relevant data. Draw the cam profile and indicate the relevant data. 14. Draw the profile of the cam when the roller follower moves with cycloidal motion as given below: Outstroke with maximum displacement of 44 mm during 180 of cam rotation Return stroke for the next 150 of cam rotation. Dwell for the remaining 30 of cam rotation. The minimum radius of the cam is 20 mm and the diameter of the roller is 10 mm. The axis of the roller follower passes through the cam shaft axis. 15. A cam, with a minimum radius of 50 mm, rotating clockwise at a uniform speed, is required to give a knife-edged follower the motion as described below: (a) To move outwards through 40 mm during 100 rotation of the cam; (b) To dwell for next 80 (c) To return to its starting position during next 90 and (d) To dwell for the rest period of revolution. Draw the profile of the cam (i) When the line of stroke of the follower passes through the centre of the cam shaft and

9 (ii) When the line of stroke of the follower is to take place with Uniform acceleration and uniform retardation. Determine the maximum velocity and acceleration of the follower when the cam shaft rotates at 900 r.p.m. (16) UNIT- IV PART A 1. Define the following terms used in Gear i. Pressure angle and ii. Module. 2. What are the roles of "Idlers" in gear trains? 3. Define the term 'arc of contact' in gears. 4. Name two applications of reverted gear train. 5. Prove or disprove that pure rolling is possible at one point only, on the line of action, between two meshing gear teeth profiles. 6. Distinguish, with suitable free hand sketches, a non-reverted gear train and a reverted gear train. 7. What are the advantages and dis-advantages of involute gear tooth profile? 8. What are the applications of inverted gear trains? 9. List down the common forms of teeth. 10. What is the condition stated by the law of gearing? 11. State the law of gearing. 12. What are the methods to avoid interference? 13. Define gear ratio. 14. Write short notes on differentials 15. Define cycloidel tooth profile and involute tooth profile. 16. Define Backlash. 17. What is gear train? 18. What are the types of gear trains? 19. Write velocity ratio in compound train of wheels? 20. Define simple gear train. 21. What is meant compound gear train? 22. What is the advantage of a compound gear train over a simple gear train? 23. What is reverted gear train? 24. What are the externally applied torques used to keep the gear train in equilibrium? 25. Where the epicyclic gear trains are used? PART B 1. Two gear wheels mesh externally to give a velocity ratio of 3 to 1. The involute teeth has 6 mm module and 20 pressure angle. Addendum is equal to one module. The pinion rotates at 90 rpm. Determine Number of teeth on pinion to avoid interference and the corresponding number on the wheel; (4) The length of path and are of contact (4) Contact ratio and (4) The maximum velocity of sliding. (4) 2. (i) Derive an expression to determine the length of path of contact between two spur gears of different size. (10) Briefly explain the sub classification of compound gear trains with neat sketches. (6) 3. (i) Explain the various pitches of helical gears with sketch. (10) (ii) Two 15 mm module 20 pressure angle spur gears have addendum equal to one module. The pinion has 25 teeth and the gear 50 teeth. Determine whether interference will occur or not. If it occurs, to what valve should the pressure angle be changed to eliminate interference? (6) 4. (i) An epicyclic gear train consists of three gears 1, 2 and 3 as shown in fig.6 the internal gear 1 has 72 teeth and gear 3 has 32 teeth. The gear 2 meshes with both gear.1 and gear 3 and is carried on an arm A. which rotates about the centre 02 at 20 rpm. If the gear 1 is fixed, determine the speed of gears 2 and 3. (12)

10 Fig. 6 (ii) Write short notes on speed ratio of a planetary gear train. (4) 5. With the help of a neatly drawn sketch of a spur gear, explain elaborately the nomenclature of gears. 6. An epicyclic gear train is shown in Fig. 14(b). The input S has 24 teeth. Gears P and C constitute a compound planet having 30 and 18 teeth respectively. If all the gears are of the same pitch, find the speed ratio of the gear train assuming A to be fixed. Fig. 14 (b) 7. (i) State and prove the law of gearing. (10) (ii) Show that the involute curves as the profiles of mating gears satisfy the law of gearing. (6) 8. A compound gear train using spur gears is required to give a total reduction ratio of 250 to 1 in four steps. The modules of the gears are 5 mm for the first step, 7 mm for the second, 10 mm for the third and 16 mm for the fourth. Arrive at the individual speed ratios, if a tolerance of ±0.2% is allowed in the total reduction ratio. (4) Find the numbers of teeth of all gears, if the minimum number of teeth for any pinion is 20. (4) Find the pitch circle diameters of all gears and the centre distances. (4) Sketch a line diagram showing the gear train. (4) 9. (i) Two unequal gears of involute profile are to give required gear ratio. Derive an expression for the minimum number of teeth required for the pinion in order to avoid interference. (12) (ii) Two gear wheels mesh externally to give a velocity ratio of 3 to 1. The involute teeth have 6 mm module and 20 pressure angle. Addendum is equal to one module. Determine the number of teeth on pinion to avoid interference and the corresponding number on the wheel. (4) 10. A reverted compound gear train is used as back gear of a lathe. It is required to give a reduction from cone-pulley speed to spindle speed of approximately 9 to 1. The module of the teeth on the high-speed pair is 4 mm and of those on low-speed pair is 5 mm. The centre distance is 180 mm. Determine the number of teeth on each of the four wheels, if the pinions are to have as nearly as possible equal numbers of teeth. Also sketch a line diagram and show the gear train. (16) 11. A pinion of 20 involute teeth and 125 mm pitch circle diameter drives a rack. The addendum of both pinion and rack is 6.25 mm. What is the least pressure angle which can be used to avoid interference? With this pressure angle, find the length of the arc of contact and the minimum number of teeth in contact at a time. 12. In an epicyclic gear train shown in Fig.2, the pinion A has 15 teeth and is rigidly fixed in the motor shaft. The wheel B has 20 teeth and gears with A, and also with annular fixed wheel D. Pinion C has 15 teeth and is integral with B(C,B being a compound gear wheel). Gear C meshes with annular wheel E, which is keyed to the machine shaft. The arm rotates about the same shaft on which A is fixed and carries the compound wheel B C. If the motor runs at 1000 rpm, find the speed of the machine shaft.

11 13. State the advantages of spur gear over helical gear. (3) Which type of gear pair is to be used to get very large speed reduction in a single stage? State the reason. (3) State and prove the fundamental law of gearing. (7) Determine the minimum number of teeth to avoid interference in worst case of meshing with 14 2 pressure angle. (3) 14. Two mating gears have 20 and 40 involute teeth of module 10 mm and 20 pressure angle. The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length. Determine the addendum height for each gear wheel, length of the path of contact, arc of contact and contact ratio. 15. State and prove the law of gearing. (5) In the epicyclic gear train shown in Fig, the compound wheels A and B as well as internal wheels C and D rotate independently about the axis O. The wheels E and F rotate on the pins fixed to arm a. All the wheels are of the same module. The number of teeth on the wheels is T A = 52, T B = 56, T E = T F = 36 Determine the speed of C if i. The wheel D fixed and arm a rotates at 200 rpm clockwise ii. The wheel D rotates at 200 rpm counter-clockwise and the arm a rotates at 20 rpm counter-clockwise. (10)

12 UNIT- V PART A 1. Differentiate between self locking and overhauling of screw. 2. State the functional difference between a clutch and a brake. 3. Why self locking screws have lesser efficiency? 4. What is meant by a self-locking and a self-energized brake? 5. Prove or disprove that the efficiency of a screw jack is independent of the load raised. 6. State the condition and the equation for the velocity of the belt for the transmission of power in a flat belt drive. 7. What is the apparent co-efficient of friction in belt drives? 8. Distinguish between sliding and rolling friction. 9. List down the laws of friction. 10. Distinguish between open and cross belt drive in terms of its application. 11. Define velocity ratio. 12. What is the maximum efficiency of the screw jack? 13. Define anti -friction bearing. 14. Differentiate multi plate clutch and cone clutch. 15. Explain velocity ratio. 16. State the law of belting. 17. What is slip? 18. What is creep? 19. What is centrifugal effect on belts? 20. What is the cross belt used instead of open belt? 21. What is wipping? 22. Why lubrication reduces friction? 23. What you meant by crowning in pulley? 24. What is brake? 25. Explain self energizing. PART B 1. Two pulleys, one 450 mm diameter and the other 200 mm diameter are in parallel shafts 1.95 m apart and are connected by a crossed belt. Find the length of the belt required and the angle of contact between the belt and each pulley. What power can be transmitted by the belt when the larger pulley rotates at 200 rpm if the maximum permissible tension in the belt is 1 kn and the co efficient of friction between the belt and pulley is 0.25? (16) 2. (i) Derive an expression for the effort required to raise a load with screw jack taking friction into consideration. (8) (ii) A 150 mm diameter value, against a steam pressure of 2 MN/m2 is acting, is closed by means of a square threaded screw 50 mm in external diameter with 6 mm pitch. If the co-efficient of friction is 0.12, find torque required to turn the handle. (8) 3. (i) Derive the force analysis of a body resting on an inclined plane with force inclined to the plane. (12) (ii) List the various types of friction. (4) 4. (i) A vertical shaft 140 mm diameter rotating at 120 rpm rests on a flat end foot step bearing. The shaft carries a vertical load of 30 KN. The coefficient of friction is Estimate the power lost is friction, assuming uniform pressure and uniform wear. (8) (ii) A multi-plate disc clutch transmits 55 KW of power at 1800 rpm. Coefficient of friction for the friction surface is 0.1. Axial intensity of pressure is not to exceed 160 KN/m 2. The internal radius is 80 mm and 0.7 times the external radius. Find the number of plates needed to transmit the required torque. (8) 5. (i) A friction clutch of multi-plate type is meant for transmitting a power of 55 kw at 1800 rpm. Coefficient of friction for the friction surfaces is 0.1. Axial intensity of pressure is not to exceed160 kn/m 2. The internal radius is 80 mm and is 0.7 timesthe external radius. Determine the number of plates needed to transmit the required torque. (10)

13 (ii) A vertical shaft of 100 mm diameter rotating at 150 rpm, rests on a flat end foot step bearing. The coefficient of friction is equal to 0.05 and shaft carries a vertical load of 15 kn. Find the power lost in friction assuming the following conditions: Uniform pressure (3) Uniform wear. (3) 6. (i) Find the power transmitted by a belt running over a pulley 700 mm diameter at 300 rpm, ji = 0.3 and angle of lap 160 and maximum tension in the belt is 2.453kN. (6) (ii) A simple brake as shown in Fig 15 (b) (ii) is used on a shaft carrying a flywheel of mass 450 Kg. The radius of gyration of the flywheel is 500 mm. and rims at 320 rpm. The coefficient of friction is 0.2 and the diameter of brake drum is 250 mm, Determine the following: (1) Torque applied due to a hand load of 150 N (4) (2) The number of turns of the wheel before it is brought to rest.(4) (3) The time required to bring it to rest from the moment of application of the brake. (2) 7. (i) In a thrust bearing, the external and internal diameters of the contacting surfaces are 320 mm and 200 mm respectively. The total axial load is 80 kn and the intensity of pressure is 350 kn/m2. The shaft rotates at 400 rpm. Taking the coefficient of friction as 0.06, calculate the power lost in overcoming the friction and the number of collars required. (8) A screw-jack has a square thread of mean diameter 60 mm and pitch 8 mm. The co-efficient of friction at the screw thread is A load of 3 kn is to be lifted through 120 mm. Determine the torque required and the work done in lifting the load through 120 mm. Find also the efficiency of the jack. (8) 8. (i) Derive an expression for the centrifugal tension in a belt passing round a pulley rim. (6) (ii) A leather belt is required to transmit 7.5 kw from a pulley 1.2 m in diameter, running at 250 rpm. The angle embraced is 165 and the coefficient of friction between the belt and the pulley is 0.3. The safe working stress for the leather belt is 1.5 MPa; the density of leather is 1000 kg/m3 and thickness of belt is 10 mm. Determine the width of the belt taking centrifugal tension into account. (10) 9. (i) A single plate clutch, with both sides effective, has outer and inner diameters 300 mm and 200 mm respectively. The maximum intensity of pressure at any point in the contact surface is not to exceed 0.1 N/mm2. If the coefficient of friction is 0.3, determine the power transmitted by a clutch at a speed 2500 rpm for two types of assumptions, that is, for uniform pressure and for uniform wear.(10) (ii) The following data related to a screw jack; Pitch of the thread screw = 8 mm, diameter of the screw thread = 40 mm, Coefficient of friction between screw and nut = 0.1, load = 20 kn. Assuming that the load rotates with screw, determine : the ratio of torques required to raise and lower the load. the efficiency of the machine. (6) 10. (i) Two pulleys, one 450 mm diameter and the other 200 mm diameter are on parallel shafts 2.1 m apart and are connected by a belt, as a cross belt drive. The larger pulley rotates at 225 r.p.m. The maximum permissible tension in the belt is 1 kn and the coefficient of friction between the belt and the pulley is Find the power that can be transmitted. (8) In a simple band brake, one end of the band is attached to the fulcrum of a lever. The other end is attached at a distance of b from the fulcrum. The effort is applied at the end of the lever. Derive an expression for braking torque, in terms of the effort. (8) 11. A single dry plate clutch transmits 7.5 kw at 900 rpm. The axial pressure is limited to 0.07 N/mm2. If the co-efficient of friction is 0.25, find mean radius and face width of the friction lining assuming the ratio of the mean radius to the face width as 4 and outer and inner radii of the clutch plate. 12. A load of 10 kn is raised by means of a screw jack, having a square threaded screw of 12 mm pitch and of mean diameter 50 m. If a force of 100 N is applied at the end of a lever to raise the load, what should be the

14 length of the lever used? Co-efficient of friction = What is the mechanical advantage obtained? State whether the screw is self locking or not. 13. A screw jack has a square thread of mean diameter 60 mm and pitch 8 mm. The co-efficient of friction at the screw thread is A load of 3 kn is to be lifted through 120 mm. Determine the torque required and the work done in lifting the load through 120 mm. Find the efficiency of the jack also. 14. (i) Prove or disprove the following statement : "AV-belt drive with same Co-efficient of friction and angle of wrap as a flat-belt drive will transmit less power than flat-belt drive". (6) (ii) Two pulleys, one 450 mm diameter and the other 200 mm diameter are on Parallel shafts 2.1 m apart and are connected by a crossed belt. The larger Pulley rotates at 225 rpm. The maximum permissible tension in the belt is 1 kn and the coefficient of friction between the belt and the pulley is Find the length of the belt required and the power that can be transmitted. (10) 15. a).a leather belt is required to transmit 7.5 kw from a pulley 1.2 m in diameter, running at 250 rpm. The angle entranced is 1650 and the coefficient of friction between the belt6 and the pulley is 0.3. If safe working stress for the leather belt is 1.5 MPa, density of leather is 1 kg/ m3 end thickness of belt is 10 mm. Determine the width of the belt taking C.F tension into account. (8) b).two pulley one 450 mm diameter and other 200mm dia are on parallel shaft 2.1 m apart and are connected by a cross belt. The larger pulley rotates at 225 rpm. The maximum permissible tension in the belt is 1 KN and the coefficient of friction between the belt and the pulley is Find the length of the belt required and the power can be transmitted. (8)