A drilling motor comprising: (a) a bearing assembly comprising: a generally cylindrical housing having an upper end and a lower end; a generally cylindrical mandrel having an upper end, a lower end configured to connect to a drill bit, and a longitudinal bore, said mandrel being coaxially disposed within the housing so as to be rotatable relative thereto about a rotational axis; radial bearing means disposed in an annular space between the housing and the mandrel; and thrust bearing means disposed in an annular space between the housing and the mandrel; (b) a generally cylindrical rotor having an upper end, a lower end, and a longitudinal bore, said rotor being coaxially disposed within the housing so as to define a generally annular working fluid space therebetween, wherein the mandrel is disposed within the bore of the rotor such that said rotor engages the mandrel so as to be coaxially rotatable therewith; (c) a plurality of elongate gates; (d) at least one axially-oriented lobe engageable with the gates during relative rotation between the rotor and the housing; (e) a plurality of fluid inlets through the mandrel and the rotor allowing fluid flow from an upper region of the rotor bore into the annular working fluid space; (f) a plurality of fluid outlets through the mandrel and the rotor allowing fluid flow out of the annular working fluid space into a lower region of the rotor bore; wherein the drilling motor defines a first fluid flow path including the fluid inlets, the annular working fluid space, and the fluid outlets, such that a flow of a working fluid along the first fluid flow path will cause relative rotation between the rotor and the housing, thereby causing each lobe to deflect each gate in sequence; and (g) further comprising flow control means disposed in the mandrel bore and configured to control the flow of the fluid along the first flow path to regulate one of a rotational speed of the rotor and mandrel or a torque applied to the mandrel. (a) a bearing assembly comprising: a generally cylindrical housing having an upper end and a lower end; a generally cylindrical mandrel having an upper end, a lower end configured to connect to a drill bit, and a longitudinal bore, said mandrel being coaxially disposed within the housing so as to be rotatable relative thereto about a rotational axis; radial bearing means disposed in an annular space between the housing and the mandrel; and thrust bearing means disposed in an annular space between the housing and the mandrel; (b) a generally cylindrical rotor having an upper end, a lower end, and a longitudinal bore, said rotor being coaxially disposed within the housing so as to define a generally annular working fluid space therebetween, wherein the mandrel is disposed within the bore of the rotor such that said rotor engages the mandrel so as to be coaxially rotatable therewith; (c) a plurality of elongate gates; (d) at least one axially-oriented lobe engageable with the gates during relative rotation between the rotor and the housing; (e) a plurality of fluid inlets through the mandrel and the rotor allowing fluid flow from an upper region of the rotor bore into the annular working fluid space; (f) a plurality of fluid outlets through the mandrel and the rotor allowing fluid flow out of the annular working fluid space into a lower region of the rotor bore; wherein the drilling motor defines a first fluid flow path including the fluid inlets, the annular working fluid space, and the fluid outlets, such that a flow of a working fluid along the first fluid flow path will cause relative rotation between the rotor and the housing, thereby causing each lobe to deflect each gate in sequence; and (g) further comprising flow control means disposed in the mandrel bore and configured to control the flow of the fluid along the first flow path to regulate one of a rotational speed of the rotor and mandrel or a torque applied to the mandrel.