I only have one of these in working order but 2-3 more to renovate. While the mechanism is a clever invention it probably fell out of fashion due to being slightly fragile, and also rapidly superseded by pedal timpani.
If you found anything on this website interesting or useful and would like to make a donation I would be extremely grateful!
With many thanks to the photographers and film makers who have allowed me to use their work; Stephen Tasker, Chris Christodolou (RCM), Tommy Pearson, Monika Rittershaus (Berliner Philharmoniker), Will Schofield, Glyn Matthews, Angus Bremner (SCO) and Zen Grisdale.