A parallel gear unit (20) for a gearbox (30) for a wind turbine includes at least two parallel shafts (21, 22), at least one of the shafts (21, 22) being supported by roller bearings (24) and each shaft (21, 22) including a gear (23, 25) with helical teeth, the gears (23, 25) of each shaft (21, 22) being adapted for meshing with each other. The parallel gear unit (20) furthermore includes a thrust collar (26) on at least one of the shafts (21, 22). In a parallel gear unit (20) according to preferred embodiments, the bearings (24) supporting the gear do not suffer from high axial forces or at least suffer less from such axial forces than prior art bearings. A gearbox (30) including the parallel gear unit (20) and a wind turbine including such a gearbox (30) are described.