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ESE Online Test Series : 2015Conventional Paper

ME : MECHANICAL ENGINEERINGTest No. - 4 | Theory of Machines

Date: 01-03-2015 | Subjectwise Test

Duration: 1 hrs. Maximum Marks: 100

Read the following instructions carefullyRead the following instructions carefullyRead the following instructions carefullyRead the following instructions carefullyRead the following instructions carefully

1. Candidate should attempt any FOURFOURFOURFOURFOUR questions out of five. Each question carries 25 marks.

2. Marks carried by each subdivision of a question is indicated at the end of subdivision.

3. Answers must be written only in ENGLISH.

4. Assume suitable data, if necessary, and indicate the same clearly.

5. Neat sketches may be drawn, wherever required.

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2 Mechanical Engineering Theory of Machines

IOTME15

Q.1Q.1Q.1Q.1Q.1 (a)(a)(a)(a)(a) A crank-rocker mechanism has a 70 mm fixed link, a 20 mm crank, a 50 mm coupler, and a 70 mmrocker. Draw the mechanism and determine the maximum and minimum values of the transmissionangle. Locate the two toggle positions and find the corresponding crank angles and the transmissionangles.

[15 marks][15 marks][15 marks][15 marks][15 marks]

(b)(b)(b)(b)(b) The angle between the axes of two shafts connected by Hookes joint is 18. Determine the angleturned through by the driving shaft when the velocity ratio is maximum and unity.


Q.2Q.2Q.2Q.2Q.2 (a) (a) (a) (a) (a) The total sleeve movement in a Hartnell governor is 3 cm. The mass of rotating balls is 1.5 kg each. Atthe mid position of the sleeve arm, which is 6.5 cm long, is horizontal. The ball arm has a length of7.5 cm. At the mid position of the sleeve, the balls rotate at a radius of 10.5 cm. Due to the maladjustment of spring, the equilibrium speed of governor at top position is 415 rpm and in lowestposition it is 430 rpm. Determine

(i) Stiffness and initial compression of spring.

(ii) Required initial compression in spring which gives equilibrium speed at the top most positionwhich is 10 rpm more than the lowest position neglect obliquity.


(b)(b)(b)(b)(b) A square threaded bolt of root diameter 22.5 mm and pitch 5 mm is tightened by screwing a nut whosemean diameter of bearing surface is 50 mm. If coefficient of friction for nut and bolt is 0.1 and for nutand bearing surface 0.16, find the force required at the end of a spanner 500 mm long when the loadon the bolt is 10 kN.


Q.3Q.3Q.3Q.3Q.3 (a)(a)(a)(a)(a) A chain drive is used for reduction of speed from 240 rpm to 120 rpm. The number of teeth on thedriving sprocket is 20. Find the number of teeth on the driven sprocket. If the pitch circle diameter ofthe driven sprocket is 600 mm and centre to centre distance between the two sprockets is 800 mm,determine the pitch and length of the chain.


(b)(b)(b)(b)(b) Two mating gears have 20 and 40 involute teeth of module 10 mm and 20 pressure angle. The addendumon each wheel is to be made of such a length that the line of contact on each side of the pitch point hashalf the maximum possible length. Determine the addendum height for each gear wheel, length of thepath of contact, arc of contact and contact ratio.


Q.4Q.4Q.4Q.4Q.4 (a)(a)(a)(a)(a) The crank-pin circle radius of a horizontal engine is 300 mm. The mass of the reciprocating parts is250 kg. When the crank has travelled 60 from IDC, the difference between the driving and the backpressure is 0.35 N/mm2. The connecting rod length between centres is 1.2 m and cylinder bore is0.5 m. If the engine runs at 250 rpm and if the effect of piston rod diameter is neglected,

calculate: 1. pressure on slide bars, 2. thrust in the connecting rod, 3. tangential force on the crank pin,4. turning moment on the crank shaft.


3ESE Online Test Series 2015 : Conventional Paper

Delhi Noida Bhopal Hyderabad Jaipur Lucknow Indore Pune Bhubaneswar Kolkata IOTME15

(b)(b)(b)(b)(b) A double-acting steam engine develops 56 kW of power at 240 rpm. The maximum and minimumspeeds do not vary more than 1% of the mean speed and the excess energy is 30% of the indicatedwork per stroke. Determine the mass of the flywheel if the radius of gyration of the flywheel is 500 mm.


Q.5Q.5Q.5Q.5Q.5 (a)(a)(a)(a)(a) Calculate the natural frequency of vibration of a two rotor system as shown below. Neglect the weightof the shaft.

a

l

W1 W2

1

2

4

6 2

60kg

92kg

15cm

25.6 cm

6.25cm

2 10 kg/cm

WWa

E

l

I


(b)(b)(b)(b)(b) A mass of 10 kg is kept on two slabs of isolators placed one over the other. One of the isolators is ofrubber having a stiffness of 3 kN/m and damping coefficient of 100 Ns/m while the other isolator is offelt with stiffness of 12 kN/m and damping coefficient of 300 Ns/m. If the system is set in motion invertical direction, determine the damped and undapmed natural frequencies of the system.


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