Drilling rig mounted on tractor unit with compact drive head arrangement

摘要

The guide mast of this drilling rig has one or more drive heads (28) sliding on the mast (24), with a driven section (42) connected to casing and drill string. A motor (48) drives the section via a pinion and gear ring, carried on a bearing in the casing (38) The gear ring (44) and bearing (40) have the same outer diameter and the ring is splined to the driven section, the latter being thrusted from above, by means of its shoulder (246). At the upper end of the driven section a holding section (250) is fitted, pref. screwed on, its lower face in contact with the upper face of the ring gear (44). The driven section (42), with holding section (250), is sealed by a shaft seal (253-260) in an opening (252) in an upper cover plate (254) of the casing (38).