A removable teeter lever and gear assembly arrangement (100) for use with a pneumatic cylinder/differential engine for operating vehicle doors. The arrangement comprises a teeter lever (16), which is associated with the vehicle doors, a gear assembly (17) having a toothed portion and an output shaft (20) extending therethrough, and at least one securing member for removably securing and/or retaining the teeter lever (16) and the gear (17) on the output shaft (20). The securing member comprises at least one retention key (18a, 19a) which allows the arrangement to be easily disassembled for maintenance and/or replacement thereof.