In a message dated 2/11/2008 11:33:34 A.M. Eastern Standard Time,
echristley@nc.rr.com writes:
But as
my
washing machine with its weak springs demonstrates, an off-center spin
can still shake the house. Washing polyester shirts, instead of
cotton
jeans, makes the shaking much less.
The imbalance of the washer is a result of part of the load being on one
side of the drum with a lessor amount of load on the opposite side. A
simple imbalance.
In the rotary the second rotor is at 180 degrees from the first in a simple
balance. The displacement along the shaft causes a wiggle in the shaft ends,
called a "rocking couple" that is completely damped by the counter weights.
Lynn E. Hanover