Abstract: A gear assembly comprising a lower gear wheel (18) and an upper gear wheel (19) contained within a housing (10, 11), the lower gear wheel being supported by bearings (20, 21) and the upper gear wheel by bearings (22, 23). The housing has wall portions (32, 34, 35, 36) which extend close to the periphery of the gear wheels so that lubricating oil, fed from a chamber (30), is entrained by the gear wheels and carried to the top of gear wheel (19) where it is diverted and fed through passages to the bearings (22, 23). Further oil carried by the upper gear wheel is diverted to passages leading to the bearings (20, 21), and excess circulating oil is returned to the chamber (30) by way of an opening (39).