A bearing cartridge for a rotatable shaft of a wind turbine comprising a shaft and a back-to-back tapered roller bearing arrangement coupled to the shaft. The bearing arrangement comprising a first bearing having a first outer ring, a first inner ring and a plurality of tapered rollers; and a second bearing having a second outer ring, a second inner ring and a plurality of tapered rollers. The bearing cartridge further comprising a gear located on the shaft between the first bearing and second bearing and a sleeve for supporting an axial load between the first and second bearings and having one or more apertures that expose the gear for coupling to an external gear.