division bell 
noun
(In Britain) a bell rung in Parliament to announce an imminent division.But it is now being increasingly overshadowed by The Cinnamon Club which can make all the difference when the division bell rings....
- Votes, which are normally sounded by the division bell, would be declared instead by ‘door keepers and police shouting and in the mansion by two gongs being sounded’.
- They emerge, of course, when the division bell rings.