PREVIOUS YEAR QUESTION PAPERS MD - 11 ( KUK )

PREVIOUS YEAR UNSOLVED QUESTION PAPERS – 1 (KURUKSHETRA UNIVERSITY)

MACHINE DESIGN - 11

QUE NO. – 1

DESIGN A PAIR OF HELICAL GEARS TO TRANSMIT 30 KW POWER AT A SPEED OF REDUCTION RATIO 4:1. THE INPUT SHAFT ROTATES AT 2000 RPM. TAKE HELICAL ANGLE AND NORMAL PRESSURE ANGEL EQUAL TO 25° & 20° RESPECTIVELY. BOTH PINION & GEARS ARE MADE OF STEEL. THE FOLLOWING DATA IS GIVEN:

PART NAME PERMISSIBLE STRESS BHN

PINION 55 MPA 340

GEAR 40 MPA 300

QUE NO. – 2

DETERMINE THE PROPER PITCH, MODULE, FACE WIDTH NUMBER OF TEETH, OUTSIDE DIAMETER OF A PAIROF 20 INVOLUTE FULL DEPTH SPUR GEARS TO TRANSMIT 112.5 KW, FROM A PINION RUNNING AT 750 RPM TO GEAR RUNNING AT 140 RPM. THE SERVICE IS INTERMITENT WITH LIGHT SHOCKS?

QUE NO – 3

SELECT A SUITABLE CHAIN DRIVE TO TRANSMIT 30 KW FROM AN ELECTRIC MOTOR TO A LINE SHAFT. MOTOR SHAFT DIAMETER IS 60MM, MOTOR RPM = 1200; LINE SHAFT IS 250; AND CENTER DISTANCE IS ADJUSTABLE FROM 600MM. SERVICE IS 10 HR/DAY, 6 DAYS PER WEEK. GOOD LUBRICATION CONDITION IS EXPECTED?

QUE NO. – 4

(A) WHAT ARE THE TWO THEORIES APPLIED TO FRICTION CLUTCH?

(B) A MULTIPLATE CLUTCH, STEEL ON BRONZE IS TO TRANSMIT 4.5 KW AT 750 RPM. THE INNER RADIUS OF THE CONTACT IS 40 MM AND THE OUTER RADIUS OF CONTACT IS 70 MM. THE CLUTCH OPERATES IN OIL WITH AN EXPECTED COEFFICIENT OF FRICTION IS 0.1. THE AVERAGE ALLOWABLE PRESSURE IS 0.35 N/MM². FIND

· THE TOTAL NUMBER OF STEEL AND BRONZE DISC?

· THE ACTUAL AXIAL FORCE REQUIRED?

· THE ACTUAL AVERAGE PRESSURE?

· THE ACTUAL MAXIMUM PRESSURE?

QUE NO.–5

IT IS REQUIRED TO DESIGN A HELICAL COMPRESSION SPRING FOR THE VALVE MECHANISM. THE AXIAL FORCE ACTING ON THE SPRING IS 300N WHEN VALVE IS OPEN AND 150N WHEN THE VALVE IS CLOSED. THE LENGTH OF THE SPRING IS 30 MM WHEN THE VALVE IS OPEN & 35 MM WHEN VALVE IS CLOSED. THE SPRING IS MADE OF OIL HARDENED & TEMPERED VALUE SPRING WIRE AND THE ULTIMATE TENSILE STRENGTH IS 1370N/MM². THE PERMISSIBLE SHEAR STRESS FOR SPRING WIRE SHOULD BE TAKEN AS 30% OF THE ULTIMATE TENSILE STRENGTH. THE MODULUS OF RIGIDITY IS 81370 N/MM²

THE SPRING IS TOBE FITTED OVER A VALVE ROD AND THE MINIMUM OUTSIDE DIAMETER OF THE SPRING SHOULD BE 20 MM. DESIGN THE SPRING AND CALCULATE

· WIRE DIAMETER

· MEAN COIL DIAMETER

· NUMBER OF ACTIVE COIL

· TOTAL NUMBER OF COILS

· FREE LENGTH OF COIL

· PITCH OF COIL

QUE NO. – 6

(A) DISCUSS AND EXPLAIN THE FOLLOWING TERMS:

· HYDRODYNAMIC LUBRICATION?

· BEARING CHARACTERISTICS NUMBER?

· SOMMER FIELD NUMBER?

· OPERATING PRESSURE?

(B) SELECT A SINGLE ROW DEEP GROOVE BALL BEARING FOR A RADIAL LOAD OF 5000N AND AXIAL LOAD OF 6000N, OPERATING AT A SPEED OF 1600 RPM FOR AN AVERAGE LIFE OF 5 YEARS AT 10 HOURS PER DAY ASSUME UNIFORM AND STEADY LOAD?

QUE NO. – 7

DESIGN A CONNECTING ROD FOR A PETROL ENGINE FROM THE FOLLOWING DATA.

DIAMETER OF PISTON = 110 MM

MASS OF RECIPROCATING PARTS, M = 2 KG

LENGTH OF CONNECTING ROD, l = 325 MM

STROKE = 150 MM

COMPRESSION RATIO = 4:1

SPEED = 1500 RPM WITH POSSIBLE OVER SPEED OF 2500 RPM

MAXIMUM EXPLOSION PRESSURE = 2.5 MPa

QUE NO. – 8

DESIGN AND DRAW A CAST IRON FLY WHEEL USED FOR A FOUR STROKE IC ENGINE DEVELOPING 180 KW AT 240 RPM THE HOOP OR CENTRIFUGAL STRESS DEVELOPED IN THE FLY WHEEL 5.2 MPa, THE TOTAL FLUCTUATION OF SPEED IS TO BE LIMITED TO 3 % OF MEAN SPEED. THE WORK DONE DURING THE POWER STROKE IS 1/3 MORE THAN AVERAGE WORK DONE DURING WHOLE CYCLE? THE MAXIMUM TORQUE ON THE SHAFT IS TWICE THE MEAN TORQUE. THE DENSITY OF CAST IRON IS 7220 KG/MM³?

PREVIOUS YEAR UNSOLVED QUESTION PAPERS – 2 (KURUKSHETRA UNIVERSITY)

MACHINE DESIGN - 11

QUE NO. – 1

(A) DEFINE LAW OF GEARING. HOW ARE THE GEAR CLASSIFIED?

(B) DEFINE FORMATIVE NUMBER OF TEETH ON A HELICAL GEAR. ALSO GERIVE THE EXPRESSION USED TO OBTAIN ITS VALUE?

QUE NO. – 2

A WORM GEAR DRIVE TRANSMITS 15 KW AT 2000 RPM TO A MACHINE CARRIAGE AT 75 RPM. THE WORM IS TRIPLE THREADED AND HAS 65 MM PITCH DIAMETER THE WORM GEAR HAS 90 TEETH OF 6 MM MODULE. THE TOOTH FORM IS TO BE 20° FULL DEPTH INVOLUTE BTHE COEFFICIENT OF FRICTION BETWEEN MATING TEETH MAY BE TAKEN AS 0.10 CALCULATE

· TANGENTIAL FORCE ACTING ON WORM?

· AXIAL THRUST & SEOERATING FORCE ON WORM?

· EFFICIENCY OF THE WORM DRIVE?

QUE NO. – 3

DESIGN BELT DRIVE TO TRANSMIT 110 KW FOR SYSTEM CONSISTING OF TWO PULLEYS OF DIAMETER 0.90 M & 1.2 M CENTER DISTANCE IS 3.6 M AND BELT SPEED IS 20 M/S. THE CO EFFICIENT OF FRICTION IS 0.3 A SLIP OF 1.2 % AT EACH PULLEY AND 5% FRICTION LOSS AT EACH SHAFT, 20% OVER LOAD ?

QUE NO. – 4

(A) DETERMINE THE MAXIMUM, MINIMUM & AVERAGE PRESSURE IN A PLATE CLUTCH WHEN AXIAL FORCE IS 4 KN. THE INSIDE RADIUS OF THE CONTACT SURFACE IS 50 MM AND OUTSIDE RADIUS IS 100 MM. ASSUME UNIFORM WEAR?

QUE NO. – 5

DESIGN A HELICAL COMPRESSION SPRING FOR A MAXIMUM LOAD OF 1000 N FOR A DEFLECTION OF 25 MM. USE VALUE OF SPRING INDEXAS 5. THE MAXIMUM PERMISSIBLE SHEAR STRESS FOR SPRING WIRE IS 420 MPa & MODULUS OF RIGIDITY IS 84 KN/MM². TAKE WAHL’S FACTOR?

QUE NO. – 6

(A) DIFFERENTIATE BETWEEN HYDRODYNAMIC LUBRICATION & WEDGE FILM LUBRICATION?

(B) DESIGN A JOURNAL BEARING TO SUPPORT A LOAD OF 5000 N AT 5000 RPM USING HARDENED STEEL JOURNAL AND BRONZE BACKED BABBIT BEARING. THE BEARING IS LUBRICATED BY OIL, ROOM TEMP IS 25°C AND OIL TEMP IS 80°C?

QUE NO. – 7

A FOUR STROKE DIESEL ENGINE HAS FOLLOWING SPECIFICATIONS:

BRAKE POWER = 5KW, SPEED = 1200 RPM, INDICATED MEAN EFFECTIVE PRESSURE = 0.35 N/MM², MECHANICAL EFFICIENCY = 80 %. DETERMINE

· BORE AND LENGTH OF CYLINDER?

· THICKNESS OF CYLINDER HEAD?

· SIZE OF STUDS FOR CYLINDER HEAD?

QUE NO. – 8

A SINGLE CYLINDER DOUBLE ACTING STEAM ENGINE DEVELOPS 150 KW AT MEAN SPEED OF 80 RPM. THE COEFFICIENT OF FLUCTUATION OF ENERGY IS 0.1 AND FLUCTUATION OF SPEED IS ± 2% OF MEAN SPEED. IF THE MEAN DIAMETER OF FLY WHEEL RIM IS 2 METER AND HUB & SPOKES PROVIDE 5% OF ROTATIONAL INERTIA OF THE WHEEL, FIND THE MASS OF THE FLY WHEEL AND CROSS SECTIONAL AREA OF RIM. ASSUME DENSITY OF FLY WHEEL MATERIAL (CAST IRON) AS 7200 KG/M³?