From Longman Dictionary of Contemporary Englishbig wheelˌbig ˈwheel noun [countable] British English 
DLOa machine used in amusement parks, consisting of a very large upright wheel with seats hanging from it, that turns round slowly SYN ferris wheel
DLOa machine used in amusement parks, consisting of a very large upright wheel with seats hanging from it, that turns round slowly SYN ferris wheelExamples from the Corpus
big wheel• He was a big wheel in Bucharest Securitate, Mr Manescu.• A big wheel in local government.• The big wheel came round our way.• The big wheel had stopped with our chair rocking sweetly at the summit. 