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 . <EOS>