Patent ID: 8893824

Claim:
A steerable system comprising a fluid powered motor having a rotor and a stator, an upstream region and a downstream region, a fluid pressure drop occurring in use, between the upstream and downstream regions, and a bias unit controlled using a valve arrangement, wherein the valve arrangement is located at the upstream region, and a bias arrangement having at least one bias pad connected to the stator so as to be rotatable therewith, the rotor being driven by a fluid flow passing along the rotor between the rotor and the stator, the at least one bias pad being actuatable against a surrounding formation to allow the application of a side load to the steerable system, the at least one bias pad being powered via a pressure drop across the fluid powered motor and by fluid passing through the fluid powered motor along a passage within an outer diameter of the stator and separate from the fluid flow passing along the rotor, wherein the fluid powered motor drives a drill bit and wherein the drill bit rotates at a different speed than the at least one bias pad.