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A 1387B.E./8.Tech.DEGREEEXAMINATION,MAY/JUNE2007'

SixthSemesterMechanical Engineering

ME 342_ DESIGN OF TRANSMISSION SYSTEMTime : Threehours Maximum : 100marks

(Approved Design Data Book is permitted)

Answer ALL questions.PARTA- (10 x2=20 marks )

1. In what way the tirning belt is superior o ordinary belt?

2. State the law of gearing.

3. What is the use of a clutch in power transmission system?4. State the advantageofherringbone gear'

5. Derive an expression or tension ratio in a belt drive'

6. Name the different friction materials used n friction clutches.

7. Draw the ray diagram for a six speedgear box'8. Name the different applications of Worrn gear'

9. Sketcha coneclutch.

10. what do you understand by simplex,duplex and triplex chain?

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11. (a )

12. (a)

13. (a)

(b)

PARTB- (5x16=80marks )

Design a chain drive to actuate a compressor rom 15 kW electric motorrunning at 1,000 r.p.m, the compressor speed being 350 rpm. Theminimum centre distance is 500 mm. The compressoroperates15 hoursper day. The chain tension may be adjusted by shifting the motor. (16)

OrDesign a V-belt drive and caiculate the actual belt tension and averagestress or the following data. Driven pulley diameter, D = 500mm, Driverpulley diameter, d = 150 mm, center distance c = 925 mm, speednr = 1000 pm, n2= 300 rpm and polver,P = ?.5 kW.

A leather belt 9 mm x 250 mm is used o drive a cast ron pulley 900mmin diameter at 336 rpm. If the active arc on the smaller pulley is 120oandstress in tight side is 2 MPa, find the power capacity of the belt. Thedensity of the leather may be taken as 980 kdt tt and coefficient of

(b)

friction of leather on cast ron is 0.35. (16)Or

Design a straight spur gear drive to transmit 8 kW. The pinion speed s720 rpm and the speed ratio is 2. Both the gears are made of the samesurface hardened carbon steel with 55 RC and core hardness less than350 BHN. Ultimate strength is 720 N/mm2 and yield strength is 360N/mm2.

Designa pair of bevel gears for trvo shafts whose axesare at right angles.The power transmitted is 25 kW. The speed of the pinion is 300 rpm andthe gear s 120 rpm.

(16)

Or(b) Design a nine-speed gear box for a machine to provide speeds ranging

from 10 0 to 1500 rpm. The input is from a motor of 5 kW at 1440 rpm.Assumeany alloy steel for the gear.

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L4. (a) Design a worm gear drive to transmit 22.5 kW at a wonn speedof 1440rpm. Velocity ratio is 24 : 1. An effrciencyof atleast 85Vos desired' Theremperature rise should be restricted to 40' C. Determine the requiredcooling area.

OrA 90' degree straight bevel gear set is needed to give a 3 : 1 reduction'Determine the pitch coneangle,pitch diameter, and gear forces f the, 25degreepressure angle pinion has 15 teeth of pitch circle diameter, 4, andthe transmitted power s 8 HP at 550 pinion rpm.Find the torque that a two surface, dry disk clutch can transmit if theoutsideand inside ining diametersare 120 mm and ?0 mm, respectively,and the applied axial force s 10 kw. Assume uniform wear and /t = 0.4 .Is the pressue on the lining acceptable?What lining material would be

(16 )

(b)

15. (a)

suitable? (16)Or

(b) In a single block brake, the diameter of the drum is 250 mm and theangle of contact is 90'. The operating force of 700 N is applied at the endof lever which is at 250 mm from the center of the brake block. Thecoeffrcientof friction between he drum and the lining is 0.35.Determinethe torque that may be transmitted. Fulcrum is at 200 mm from thecentre of brake block with an offset of 50 mm from the surfaceof contact.

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