Inertia in gears - key, wippen, hammer combined inertia formula

[Mark Davidson]

Found a web page that describes how to calculate moment 
of inertia of two gears:

http://www.tech.plym.ac.uk/sme/desnotes/gears/gearaccel.htm

Basically, if inertias are Ia and Ib, and relative speed of
second gear is n, then total inertia is:

Ia + n^2*Ib

Can use this to find total key/wippen/hammer 
inertia as follows:

Let key, wippen, and hammer moments be Ik, Iw, Ih

Further let 

Ko = key "out" lever arm = balance rail to capstan 
Wi = wippen "in" lever arm = capstan to wippen center
Wo = wippen center to jack/knuckle contact
Hi = jack/knuckle contact to hammer center.

Relative angular speed of wippen to key would be Ko/Wi.
Relative angular speed of hammer to wippen would Wo/Hi.

Then total inertia would be

Ik + (Ko/Wi)^2*(Iw + (Wo/Hi)^2*Ih)

or:

Ik + (Ko/Wi)^2*Iw + ((Ko/Wi)*(Wo/Hi))^2*Ih

-Mark