DOM QUESTION PAPER - 4

QUESTION PAPER – 3

DYNAMICS OF MACHINES

QUE NO 1:-

(A) FOLLOWING DATA RELATES TO A HORIZONTAL RECIPROCATING ENGINE:-

WEIGHT OF RECIPROCATING PARTS                                    =1.250 KN

WEIGHT OF CONNECTING ROD                                  =1.00 KN

LENGTH OF STROKE                                                        =220 MM

LENGTH OF CONNECTING ROD                                  =440 MM

DISTANCE OF C.G. FROM BIG END CENTRE                        =180 MM

ENGINE SPEED                                                                    =750 R.P.M.

FIND THE RESULTANT INERTIA TORQUE ON THE CRANK-SHAFT WHEN THE CRANK MAKES AN ANGLE OF 30 DEGREES WITH INNER DEAD CENTRE.

QUE NO 2:-

THE TURNING MOMENT DIAGRAM FOR A MULTI CYLINDER ENGINE IS TO A SCALE OF 1 CM TO 3 KN-M VERTICALLY AND 1 CM TO 30 DEGREE HORIZONTALLY. THE INTERCEPTED AREAS BETWEEN OUTPUT TORQUE CURVE AND MEAN RESISTANCE LINE, TAKEN IN ORDER FROM THE LEFT HAND ARE:-

-0.52, +1.24, -0.92, ++1.4, -0.85, +0.72, -1.07 SQ. CM.

WHEN THE ENGINE IS RUNNING AT 800 RPM AND WEIGHT OF FLYWHEEL IS 5 N. TOTAL FLUCTUATION OF SPEED DOES NOT EXCEED 2 PERCENT OF MEAN SPEED. WHAT IS THE VALUE OF RADIUS OF GYRATION?

QUE NO 3:-

(A) DRAW AN INTERNAL EXPANDING SHOE BRAKE AND EXPLAIN ITS WORKING PRINCIPLE, ALSO DEDUCE EXPRESSION FOR TORQUE AND MOMENTS.

(B) WITH NEAT SKETCH, EXPLAIN THE WORKING OF WILSON-HARTNELL GOVERNOR AND DETERMINE AN EXPRESSION FOR ITS EQUILIBRIUM SPEED.

QUE NO 4:-

A SHAFT CARRIES FOUR WEIGHTS P,Q,R,S WEIGHTING 120 N, 200 N, 300 N AND 160 N RESPECTIVELY SPEED 450 MM APART. MEASURING ANTI-CLOCKWISE FROM P,Q MAKES 240 DEGREE ,R MAKES 135 DEGREE AND S MAKES 270 DEGREE. THE RADII ARE 400,300,150, AND 450 MM AND SHAFT RUNS AT 180 RPM. FIND THE MAGNITUDE AND DIRECTION RELATIVE TO P OF THE UNBALANCED FORCE AND COUPLE ABOUT A PLANE MIDWAY BETWEEN P AND Q.

QUE NO 5:-

(A) DETERMINE THE MINIMUM NUMBER OF TEETH ON PINION IN INVOLUTE RACK IN ORDER TO AVOID INTERFERENCE.

(B) A PAIR OF SPUR GEARS WITH 21 AND 30 TEETH ARE OF INVOLUTES PROFILE AND PRESSURE ANGLE 20⁰. FIND THE MAXIMUM ADDENDA ON PINION AND GEAR TO AVOID INTERFERENCE IF MODULE IS 6 MM. ALSO FIND THE MAXIMUM VELOCITY OF SLIDING ON EITHER SIDE OF PITCH POINT IF PINION RUNS AT 3000 RPM.

QUE NO 6:-

(A) DESCRIBE A DIFFERENTIAL GEAR AND PROVE THAT TWO GEAR WHEELS WILL ROTATE AT DIFFERENT SPEEDS WHEN ROUNDING A CURVE PATH.

(B) WHAT DO YOU MEAN BY INTERFERENCE IN INVOLUTE PROFILE GEARS? WHAT ARE THE METHODS TO AVOID IT? EXPLAIN NEAT SKETCH.

QUE NO 7:-

(A) DERIVE AN EXPRESSION FOR THE COUPLE THAT COMES IN PICTURE WHEN A WHEEL ROTATES WITH UNIFORM ANGULAR VELOCITY AND HAS A GIVEN PRECESSIONAL MOTION.

(B) A LOCOMOTIVE MOVES AT A SPEED OF 100 KM/HOUR TURNS ROUND A CURVE OF 500 METERS RADIUS TO THE RIGHT. THE PAIR OF DRIVING WHEELS ARE 2 M IN DIAMETER AND ALONG WITH AXLE WEIGH 2 TONES. THE RADIUS OF GYRATION OF THE WHEELS TOGETHER WITH AXLE IS 0.6 M. FINDS THE GYROSCOPIC EFFECT ON THE PAIR OF DRIVING WHEELS.

QUE NO 8:-

(A) EXPLAIN, WITH NEAT SKETCHES THE BLOCK DIAGRAMS AND THEIR IMPORTANCE IN CONTROL DEVICES.

(B) ESTABLISH AN EXPRESSION FOR THE TRANSFER FUNCTION OF SPRING CONTROLLED GOVERNOR.