This stop, really an accessory, consisted of two (or more, according to Grove) large, loud, stopped wooden pipes, intended to give the effect of kettledrums when played staccato. According to Audsley and Grove, the pipes were often tuned at an interval of a fifth, apparently intended to be played independently, in imitation of the usual usage of a pair of kettledrums. According to Wedgwood, this stop sounded the two lowest pipes in the organ, producing a rolling effect from the resultant tone.
No examples of Drum Pedal or Timballo are known. Contributions welcome.