A rotary valve comprising: a valve body, a valve seat disposed within the valve body, and a closure member disposed within the valve body and movable relative to the valve seat via a drive shaft to control fluid flow through the valve body, and a thrust bearing comprising: a cylindrical body, and a journal portion sized to be disposed between the valve body and the drive shaft; characterized in that the thrust bearing comprises a thrust portion sized to be disposed between the valve body and the closure member, the thrust portion having a first flat surface located between the valve body and the closure member and spaced apart from each of the valve body and the closure member, and a second flat surface seats against a corresponding flat surface of the valve body when the bearing is subject to a combined thrust and torsional load via the drive shaft, such that the bearing can accommodate the combined thrust and torsional load wherein the thrust portion comprises a D-shaped bearing flange that extends radially outward from the cylindrical body adjacent or proximate to one end of the cylindrical body, and wherein the D-shaped bearing flange is defined by a chamfered portion with a flat edge and a cylindrical portion, said cylindrical portion comprising a pair of shoulders defining the first flat surface and the second flat surface, which extend radially inward from the flat edge. a valve body, a valve seat disposed within the valve body, and a closure member disposed within the valve body and movable relative to the valve seat via a drive shaft to control fluid flow through the valve body, and a thrust bearing comprising: a cylindrical body, and a journal portion sized to be disposed between the valve body and the drive shaft; characterized in that the thrust bearing comprises a thrust portion sized to be disposed between the valve body and the closure member, the thrust portion having a first flat surface located between the valve body and the closure member and spaced apart from each of the valve body and the closure member, and a second flat surface seats against a corresponding flat surface of the valve body when the bearing is subject to a combined thrust and torsional load via the drive shaft, such that the bearing can accommodate the combined thrust and torsional load wherein the thrust portion comprises a D-shaped bearing flange that extends radially outward from the cylindrical body adjacent or proximate to one end of the cylindrical body, and wherein the D-shaped bearing flange is defined by a chamfered portion with a flat edge and a cylindrical portion, said cylindrical portion comprising a pair of shoulders defining the first flat surface and the second flat surface, which extend radially inward from the flat edge. a cylindrical body, and a journal portion sized to be disposed between the valve body and the drive shaft; characterized in that the thrust bearing comprises a thrust portion sized to be disposed between the valve body and the closure member, the thrust portion having a first flat surface located between the valve body and the closure member and spaced apart from each of the valve body and the closure member, and a second flat surface seats against a corresponding flat surface of the valve body when the bearing is subject to a combined thrust and torsional load via the drive shaft, such that the bearing can accommodate the combined thrust and torsional load wherein the thrust portion comprises a D-shaped bearing flange that extends radially outward from the cylindrical body adjacent or proximate to one end of the cylindrical body, and wherein the D-shaped bearing flange is defined by a chamfered portion with a flat edge and a cylindrical portion, said cylindrical portion comprising a pair of shoulders defining the first flat surface and the second flat surface, which extend radially inward from the flat edge.