At a particular rotational speed, the unbalanced force due to revolving mass
Magnitude = mω2r .
It direction is perpendicular to the perphering of rotational envelope in the same plane which changes at every angle.
Unbalance in high speed rotating machine parts may be due to
1. imperfect machining
2. non-symmetry of parts
3. non-homogeneity of materials
4. in accuracy of pitch of blades
Which of these statements are correct?
Consider a 6 tonnes rotor of a steam turbine running at 8000 rpm out to the extent of 0.2 cm. The centrifugal force tending to lift the turbine from its foundations will be about
Consider a mass m attached at radius r from the axis of shaft which rotates with an angular velocity ω. The balancing is achieved by mounting a B kg mass at radius bfrom the axis of shaft. If the speed of shaft is doubled, then to attain perfect balance, the value of mass B should be
∴ The value of balancing mass does not depend upon speed of rotation.
For balancing a single disturbing mass, the minimum number of balance masses required to be introduced in a piane parallel to the plane of rotation of the disturbing mass will be
Which one of the following can completely balance several masses revolving in different planes on a shaft?
Two balancing masses in different planes can completely balance several masses revolving in different planes.
A system of masses rotating in different parallel planes is in dynamic balance if the resultant
Condition for dynamic balancing ∑F = 0 and ∑M = 0.
A system in dynamic balance implies that
Unbalanced force is produced due to eccentricity in the foliowing, except
if the planes of rotation of the three masses are parallel, then the balance mass B1 is
16 × 50 = B1 × 40 + B2 × 60
⇒ 4B1 + 6B2 = 80
B1 × 40 × 50 = B2 × 60 × 75
⇒ B2 = 0.44B1
Now, 6.667B1 = 80
⇒ B1 = 12 kg