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KONERU LAKSHMAIAH COLLEGE OF

ENGINEERING

(Autonomous)

Division of Mechanical Engineering

ASSIGNMENT TEST-I FOR ? B.Tech 2010-11(I-SEM)

Subject: Dynamics of Machines

Date: 10-08-2010

Max. Marks: 10

Max. Time: 45 min

1. A shaft is rotating at a uniform angularspeed. Masses m1, m2, m3 and m4 of

magnitudes 300kg, 450kg, 360kg and 390kgare rigidly attached to a shaft. The massesare rotating in the same plane. Thecorresponding radii of rotation are 200mm,150mm, 250mm and 300mm respectively.The angles made by these masses withhorizontal are 0o, 45o, 120o and 225o. Findthe magnitudes and directions of balancingmass if its radius of rotation is 200mm.

2. A shaft carries four masses A, B, C, andD of magnitudes 200kg, 300kg, 400kg and200kg respectively and revolving at radii80mm, 70mm, 60mm and 80mm in planesmeasured from A at 300mm, 400mm and700mm and to the right of A. The anglesbetween the cranks measured anticlockwiseare A to B 45o, B to C 70o and C to D 120o.The balancing masses are to be placed inplanes X and Y. The distance between theplane A and X is 100mm, between X and Y is400mm and between Y and D is 200mm. Ifthe balancing masses revolve at a radius of100mm, find their magnitudes and angularpositions.

3. A rotating shaft carries four radialmasses A= 8kg, B & C= 6kg, and D= 5kg.

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The mass centers are 30mm, 40mm, 40mmand 50mm respectively from the axis of theshaft. The axial distance between the planesof rotation of A and B is 400mm and between

B and C is 500mm. The masses A and C areat right angles to each other. Find for acomplete balance, (a) the angle between themasses B and D from mass A, (b) the axialdistance between the planes of rotation of Cand D, and (c) the magnitude of mass B.

4. A single cylinder horizontal engine runsat 120rpm with a stroke of 400mm. Themass of the revolving parts assumedconcentrated at the crank pin is 100kg andmass of the reciprocating parts is 150kg.Determine the magnitude of the balancingmass to be placed opposite to the crank at aradius of 150mm which is equivalent to allthe revolving and 2/3rd of the reciprocatingparts. If the crank turns 30o from the inner

dead centre, find the magnitude of theunbalanced force due to the balancing mass.

5. A four cylinder engine has the two outercranks at 120o to each other and theirreciprocating masses are each 400kg. Thedistance between the planes of rotation ofadjacent cranks are 400mm, 700mm,700mm and 500mm. Find the reciprocating

mass and the relative angular position foreach of the inner cranks, if the engine is tobe in complete primary balance. Also find themaximum unbalanced secondary force, if thelength of each crank is 350mm, the length ofeach connecting rod 1.7m and the enginespeed 500rpm.

6. The pistons of a 60o twin V-engine has

strokes of 120mm. The connecting rod

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driving a common crack has a length of200mm. The mass of the reciprocating partsper cylinder is 1kg and the speed of thecrank shaft is 2500rpm. Determine the

magnitude of the primary and secondaryforces.

TEXT BOOKS / REFERENCE BOOKS:

1. Mechanism and Machine Theory by J.E. Shigley

2. Theory of Machines and Mechanisms by

C.S.Sharma, Purohit

3. Theory of Machines by T. Bevan

4. Theory of Mechanisms and Machines byA. Ghosh and A.K. Mallik.

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