IMPROVEMENTS IN OR RELATING TO A SECONDARY DRIVE UNIT
A secondary drive unit (10) for demountable attachment to a machine having a primary drive unit and power take-off, the secondary drive unit (10) comprises a housing (12), a directly or indirectly attachable to said machine, a drivable input element (16) drivable by the machine at or adjacent to one end of the housing (12), a driven output element (18) at or adjacent to the other end of the housing (12) for driving a tool and/or another machine, and at least one rotatable gear carrier (44) in the housing (12) drivable by the drivable input element (16). An interior surface of the housing (12) includes a radially- inwardly projecting gear-carrier stop (58) overlapping an upper edge of the gear carrier (44). A low-friction rubbing element (62) formed of a low-friction material relative to that of the housing (12) is interposed between the gear-carrier stop (58) and the gear carrier (44) to prevent or limit gear-carrier lift. This thus prevents or limits undue lateral strain along a central rotational axis of the drive unit (10), and thus a possibility of internal shearing.