Vierradantrieb mit zweistufiger Nachschaltgruppe

摘要

A drive unit for a four-wheel drive vehicle has a main gearbox and a subsequent range box. An annular gear (11) of a first planetary gearing (9) which gives a range change is driven from the main gearbox and a second planetary forming a center transfer differential gearing (10) comprises an annular gear (16) and a sun gear (18), each being drivingly connected with either of the driven axles. A planet carrier (12) is integral with the planet carrier of the first planetary gearing (9). The sun gear (14) of the first planetary gearing (9) is drivingly connectable to either the planet carrier (12) or the casing (7; 70; 73) by means of a shifting coupling (30). The shifting coupling (30) comprises a shifting sleeve arranged within the sun gear (14) provided with at least one first set of splines (32) and selectively engaging a set of inside splines (36) of the sun gear (14) of the first planetary gearing (9) and selectably engaging either a set of splines (37) of the casing (7) or a set of splines (38) of the planet carrier (12). The shifting sleeve can preferably be actuated to lock the central differential but an end part (71) of the sleeve may be omitted if locking is not required. <IMAGE>