Another variation of the ratchet wheel snare drum beater, which I saw
and photographed on an organ I believe to have been made by Wurlitzer,
has only two beater sticks, and the ratchet wheels turn continuously,
driven by belting from the crankshaft in the usual manner.

When drum activity is called for, a rather large pneumatic under the
shelf pulls the beaters into engagement with the ratchet wheels.  This
mechanism was working nicely at the time I saw it.

Jules Shaffer