MACHINE DESIGN 2 PAPER 2

DOWNLOAD MECHANICAL ENGINEERING PREVIOUS YEARS QUESTION PAPERS PTU B.TECH

MECHANICAL DESIGN II ME 302 6th/7th Sem May 2k
Max marks 60

Note: Section A is compulsory. Attempt any Four questions from Section B and any Two questions from Section C. Use of design data book is allowed.

Section A Marks 2 each

1.
(a) Discuss oil pressure distribution for journal bearing for hydrodynamic bearing.

(b) Name different stresses developed in flywheel.

(c) Discuss the characteristics and advantages of involute tooth profiles.

(d) How does the coefficient of friction in worm gearing vary with rubbing velocity?

(e) What is the most likely mode of failure of a worm gearing?

(f) What is meant by life of antifriction bearing?

(g) Enlist the factors on which the value of coefficient of fluctuation of speed depends.

(h) Design of disc clutch is based on uniform wear. Specify the reasons.

(i) Discuss the advantages and disadvantages of short center distance belt drives.

(j) What is chordal action in chain drives?

Section B Marks 5 each]

2. A compressor running at 300 rev/min is driven by a 15 kW 1200 rev/min motor through a 14 ½ degree full depth gears. The center distance is 0.375 m. The motor pinion is to be of C-30 forged steel hardened and tempered, and the driven gear is to be of cast steel. Assuming medium shock condition:
Determine the module, the face width, and the number of teeth on each gear.

3. Determine the power capacity of a pair of helical turning gears having a transmission ratio of 10:1. The teeth are 20 degree full depth involute, 6 mm module. The pinion has 25 teeth and rotates at 5000 rev/min. The active face width is 76 mm and the material is C-40 steel untreated.

4. A semi-elliptical spring is to carry a load of 5000 N and consists of 8 leaves 46 mm wide, two of the leaves being of full length. The spring is to be made 1000 mm between the eyes and is held at the center by a 60 mm wide band. Assume that the spring is initially stressed so as to induce an equal stress of 500 N/mm2 when fully loaded. Design the spring giving:
(a) thickness of leaves
(b) eye diameter
(c) length of leaves
(d) maximum deflection and camber

5. A V-belt transmits 11 kW at 900 rev/min of the smaller sheave. The sheave pitch diameters are 173 mm and 346 mm. The center distance is 0.76 m. If the maximum permissible working force per belt is 560 N, determine the number of belts required if the coefficient of friction is 0.15 and the groove angle of the sheaves is 34 degrees. The belt mass =0.194 kg/m.

6. A multiple disk clutch, steel on bronze is to transmit a4 kW at 750 rpm. The inner radius of contact is 40 mm and the outer radius of contact is 70 mm. The clutch operates in oil with an expected coefficient of friction 0.10. The average allowable pressure is 350 kN/m2.
(a) How many total disks of steel and bronze are required?
(b) What is the average pressure?

Section C Marks 10 each

7. A full journal bearing of diameter 0.075 m and a length 0.125 m is to support a load of 20 x 103 N at the shaft speed of 1000 rev/min. The bearing temperature is to be limited to 77 degree C in a room temperature of 38 degree C. The viscosity of the oil used is 0.0098 kg/ms at 116 degree C. Find the amount of artificial cooling required by means of external oil cooler.

8. A compressor is to actuated from 10 kW electric motor. The speed of the motor shaft is 970 rpm and that of compressor is to be 330. The compressor operates in two shifts. The minimum centre distance should be 550 mm. Design a suitable chain drive.

9. A single cylinder double acting steam engine delivers 187.5 kW at 100 rpm. The maximum fluctuation of energy per revolution is 15 percent of the energy developed per revolution. The speed variation is limited to 1 percent either way from the mean. The mean diameter of the rim is 2.4 m. Design and draw flywheel.