Dom Qbank III

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SBM COLLEGE OF ENGINEERING & TECHONOLOGY, DINDIGUL-624005.

DEPARTMENT OF MECHANICAL ENGINEERING

Bra!" # M$!"a%!a S'()$!* # D+a%! O Ma!"%$r+

Y$ar # III S'()$!* C/$# ME101

S$ # 3 Fa!'*+ # Mr.M.Sa(ar$$ara

UESTION BAN

UNIT 7II BALANCING

T8O MAR UESTIONS

1. 8"a* % +a%! (aa!%9: ;A?

A system of rotating masses is said to be in static balance if the combined mass centre of

the system lies on the axis of rotation.

2. 8"a* ar$ *"$ %$r$* *+


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%o. A single cylinder engine cannot be fully balanced. &ecause the unbalanced forces

due to recirocating masses remains constant in direction but varies in magnitude.

. D$%$ Ha$r (/ %*" r$. D$%$ a+%9 !/'


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15. D%$r$*%a*$ ($*$$ *a*%! a +a%! (aa!%9. ;A,2010?

S.NO S*a*%! Baa!%9 D+a%! Baa!%9

The dynamic forces as a result of the

unbalanced masses are balanced by

introducing balancing masses in the lane

of rotation or different lanes.

The arrangement made in static balancing gives

rise to a coule #hich tends to roc" the shaft in

bearing.

/'t deals only #ith balancing of dynamic

forces

't deals #ith balancing of dynamic force and

balancing of coule due to dynamic force.

16. 8"a* % $a* (+ (aa!%9 / r/*a*%9 a$: ;N/@=D$! 200?

The rocess of roviding the second mass in order to counter act the effect of the centrifugal

force of the unbalanced first mass is called balancing of rotating masses.

1. E


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The distance of the lanes A/, A5and A4 are /9 mm, 4/ mm and 9/ mm resectively from lane

A. The angle measured counter cloc"#ise are mto m/ 42-, m/to m5 92- and m5to m4 52-. The

distance bet#een the balancing lanes ; and 1 are 2 mm and ; is / mm from A and 1 is

mm from A4. 'f the balancing masses revolve at a radius of 9/ mm. find their magnitude and angular

ositions. (%ov8Dec /5,/)

5. A, &, * and D are four masses carried by a rotating shaft at radii , /2 and / and 2 mm

resectively. The lanes in #hich the masses revolve are saced : mm aart and the masses of &,

* and D are

(ii) A shaft carries five masses A, &, *, D and ? #hich revolves at the same radius in lanes

#hich are e=uidistant from one another. The magnitude of A, *,D are 2 "g, 4 "g, 6 "g

resectively. The angle bet#een A and * is +- and that bet#een * and D is 52-. Determine

the magnitude of the masses in lanes & and ? and their ositions to ut the shaft in comlete

rotating balance. (%ov8Dec /:)9. 0our masses m, m/, m5and m4attached to a rotating shaft on the same lane are / "g, 5 "g,

/4 "g and /: "g resectively,. The corresonding radii of rotation are ./ m, .2 m, ./2 m and

.52 m resectively and the angles bet#een successive masses are 42-, 92- and 52-. 0ind the

osition and magnitude of the balance mass re=uired if its radius of rotation is ./m.

(%ov8Dec /9)6. 0our masses m, m/, m5and m4attached to a rotating shaft on the same lane are / "g, 5 "g, /4

"g and /: "g resectively,. The corresonding radii of rotation are /mm, 2mm, /2 mm and

5mm resectively and the angles bet#een successive masses are 42-, 92- and 52-. 0ind the

osition and magnitude of the balance mass re=uired if its radius of rotation is /mm.

(%ov8Dec /9)

4


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+. A shaft carries four masses A, &, * and D of magnitude / "g, 5 "g,4 "g and / "g

resectively and revolving at radii of 6 mm, 9 mm, : mm and 6 mm in lanes measured from A

at 5 mm, 4 mm and 9 mm. the angles bet#een the cran"s measured A*@ are A to & 42-, & to

* 9- and * to D /-. The balancing masses are to be laced in lanes and B. the distance

bet#een the lanes A and is mm. bet#een and B is 4 mm. bet#een B and D is / mm. if

the balancing masses revolve at a radius of mm. find their magnitude and the angular ositions.

(Aril81ay /+) (%ov8Dec /+). A, &, * and D are four masses carried by a rotating shaft at radii , / and / and 2

resectively. The lanes in #hich the masses revolve are saced 2 mm aart and the masses of &,

* and D are

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