Patent ID: 8499858

Claim:
An apparatus, comprising: a drilling rig; a drill string extending within a borehole in a subterranean formation; and a top drive apparatus comprising a spindle and a top drive housing, wherein the top drive is suspended from the drilling rig via an interface to the a top drive housing, wherein the drill string is suspended from the top drive apparatus via an interface to the spindle, and wherein the top drive apparatus further comprises: a bearing coupled between the spindle and top drive housing; a gearbox coupled between the spindle and top drive housing; a bearing lubrication system fluidly coupled to the bearing and not the gearbox; and a gearbox lubrication system fluidly coupled to the gearbox and not the bearing, wherein: the gearbox lubrication system is to operate in the presence of forced lubricant circulation; the bearing lubrication system is to operate in the absence of forced lubricant circulation; the gearbox lubrication system is to operate in the presence of lubricant filtration; the bearing lubrication system is to operate in the absence of lubricant filtration; the bearing lubrication system comprises a sump, a reservoir, and a riser coupled to the sump and the reservoir; and the riser is fluidly coupled to the bearing.