Janardan Rai Nagar Rajasthan Vidyapeeth 2007 Diploma Mechanical Engineering THEORY OF MACHINES - Question Paper

Model Question Papter

DSM7 - THEORY OF MACHINES

Time : 3 hrs Maximum marks : 75

 

Instruction:

1. Question paper is divided into Group A, Group B and Group C

2. Each Group is 25 Marks

3. Figure to the right in bracket indicates marks.

4. Good Handwriting is expected

5. Assume suitable data if necessary.

 

Group A (25 Marks)

 

Answer any three questions (Question 1 is compulsory)

 

Q.1 Define link, kinematic pair. Classify kinematic pair on various accounts. (5)

Q.2 Write a short notes on:

(a)                Sensitivity,

(b)               Hunting,

(c)                Stability,

(d)               Effort and power of a governor. (10)

Q.3 (a) Estimate a formula for maximum efficiency of a screw jack.

(b) Derive a formula for torque for a flat collar bearing. (10)

Q.4 Prove that length of an open belt drive

L = (p/2) (D1 + D2) + 2x + (D1 - D2)²/ 4x

Where D1 and D2 are the diameters of larger and smaller pulley and

x = distance between the center of two pulleys. (10)

Q.5. Explain beam engine

 

Group B (25 Marks)

 

Answer any three questions (Questions 6 is compulsory)

Q.6. The weights of four masses W₁ , W₂ , W₃ & W₄ are respectively 2 KN, 3 KN, 2.4KN and 2.6KN. The corresponding radii of rotation are 200 mm , 150 mm, 250 mm and 300 mm and the angles are 45^o , 75^o and 135 ^o . Find the position and magnitude of the balance weight required if the radius of rotation is 200 mm? (5)

Q.7. Cam with 25mm minimum radius has to give the motion to the roller follower 10 cm dia as follows : a) Follower to complete outward stroke of 25 mm during 110^o of cam rotation with S.H.M b) Follower to return to its initial position during next 90⁰ of cam rotation with uniform acceleration and retardation. Lay out the cam profiles when, (10)

a)      The follower axis passes thro centre of cam.

b)      The follower axis is offset by 20 mm w.r.t. cam centre.

Q.8. The band brake as shown in figure has an angle of contact = 210 ⁰ to sustain a torque of 400 N-m . The band has a compressed with woven lining and bears against a cast iron drum of 350 mm diameter. Find the force F. Take =0.25 , a = 35mm, b = 150 mm and

c= 500mm. Find the value of b for which the brake is self locking? (10)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Q.9. Draw profile of cam which gives a reciprocation motion to a knife edged follower as below.

a)      The follower moves out through a stroke of 35 mm during 120o of cam rotation(10)

b)      It dwells for next 60^o.

c)      Returns during next 105^o

d)      Dwells for remaining part of the cam rotation

The follower performs SHM during both the strokes. The minimum radius of cam is 3 cm. The line of motion passes through the center of cam

Q.10. Discuss the various types of transmission dynamometer. (10)

Group C (25 Marks)

All Questions are Compulsory.

 

Q.11 Fill in the blanks ( each question carry 2 marks)

1. The product of the diametral pitch and circular pitch is -------------.

2. In a structure, the number of degree of freedom is -------------------.

3. In a kinematic chain, a quaternary joint is equivalent to ---------- binary joints

4. The train value of a gear train is ------------ velocity ratio of a gear train.

5. In a ----------- cam, the follower moves in direction perpendicular to the cam axis.

 

Q.12 Multiple choices Question (Each question carries 2 marks)

1)In conical collar bearing aerial load W is equal to

a)      2Πp( r1-r2)

b)      Πp( r12 r2 2)

c)      2Πpc(μ+ r2)

d)      none

2)Belt device is

a)Positive device

b) Neutral device

c) Negative device

d) Both a and b

 

3)Spur gears are having

a)Helical tooth c) Both a and b

b)Straight tooth d) None of these

4)Module is equal to

a)d/T

b) T/d

c) Txd

d)Atx

5) In mechanism

a) No link is fixed

b) One link is fixed

c) All the link are fixed

d) Can be any

 

Q.13 True or false (each question carry 1 marks).

 

1)      In Kinematic chain L = 2P-4

2)      Pitch point is the point where pressure angle is minimum

3)      V belts are used with large center distance

4)      Bevel gears are used to connect two shafts at some angle

5)      Frequency of natural vibration is given by

 

 

 

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