There are two main types of clock striking mechanisms - the Locking Plate and the Rack Striking.
The Locking Plate mechanism uses a notched plate to control the strikes. The plate revolves twice a day, and therefore has twelve notches, one for each hour. There are 72 bell strikes in any twelve hour interval. The distance between the notches determines the number of strikes. The plate is not in fact locked by a lever, but rather the notches provide a template into which a lever can fall, thus preventing the gear train from revolving.
The illustration shows the Meccano Locking Plate mechanism, still under development.
The Rack Stike depends on a snail which a spiral shaped cam, against whih a feeler rests. The distance of the feeler from the centre of the cam determines the number of strikes. Attached to this feeler is a rack, which is lifted one tooth at a time as the bell is struck. The Meccano Cam part 131 could be used as the snail if its action is amplified. Such a mechanism would be fascinating if it were to be built in Meccano.