Many components such as clutches, brakes, couplings, drive belts, etc. are used in applications where starting, stopping or reversing of a load is involved. Factors and formulas needed to establish the power requirements are given here.
Kinetic Energy of Relation
Starting from basic equation
E = mV² .........ft lb
(1)
2
where
| m is mass =
W in slugs i.e. lb/sec² G ft V is velocity in ft sec |
W = weight in lbs. G = gravitational acceleration in ft/sec² (G = 32.2 ft/sec² = 386 in/sec²) |
If we assume that the entire mass is concentrated at the radius of gyration k then we can substitute
V = 2kpN ....
ft where N is in RPM; k is in feet
60
sec
Substituting values for V and G in the basic equation we obtain
E = Wk²
. N² = Wk²N²
..............ft
lb
(2)
G 182.5 5878
Inertia
In simple terms, Inertia is the property of a body at rest to stay at rest, or in motion to remain in motion.
Expression = Wk²
=IG is known as mass moment of Inertia and is given in ft. lb.
sec².
G
Often, expression Wk² = I in lb. ft² is used as "moment of inertia in weight units. It is proportional to IG and its proportionality factor G = 32.2 is often lumped with other constants.
T15
