Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 175)

Reference 10-13
WK
2
or WR
2
Where:
WR
2
refers to the inertia of a rotating member that was calculated by
assuming the weight of the object was concentrated around its rim at a
distance R (radius) from the center (e.g., flywheel).
WK
2
refers to the inertia of a rotating member that was calculated by
assuming the weight of the object was concentrated at some smaller
radius, K (termed the radius of gyration). To determine the WK
2
of a part,
the weight is normally required (e.g., cylinder, pully, gear).
Torque Formulas
Where:
T = Torque (ft.-lb.)
HP = Horsepower
N = Speed of motor at rated load (RPM)
Where:
T = Torque (ft.-lb.)
F = Force (lbs.)
R = Radius (ft.)
Where:
T = Torque (ft.-lb.)
WK
2
= Inertia reflected to the Motor Shaft (ft.-lb.
2
)
D RPM = Change in speed
t = Time to accelerate (sec.)
Note: To change ft.-lb.
2
to in-lb-sec.
2
: Divide by 2.68
To change in-lb-sec.
2
to ft.-lb.
2
: Multiply by 2.68
T
HP 525
×
N
---------------------- =
T F R
×
=
T (Accelerating
WK
2
∆
RPM
( ) ×
30 8t
Ч
--------------------------------- =