A tensioning system comprising: a base; an arm pivotally coupled to said base, said arm having an engagement surface and being configured to pivot relative to said base about a pivot axis; a biasing mechanism operatively coupled to said arm to bias said arm relative to said base; a bushing having a cyclindrical portion at one end of the bushing and a flange portion at the other end of the bushing, or separate bushings comprising a cylindrical bushing and a spring bushing positioned between said arm and said base; a cover fixedly coupled to said base at an axial end thereof; wherein the cylindrical portion or the cylindrical bushing is positioned radially between an inner flange of the arm and said base, thereby providing radial alignment between said arm and said base; wherein the flange portion or the flange bushing is positioned axially between an end flange of the base and a connecting portion of the arm, thereby providing axial alignment between the arm and the base; wherein sufficient wear in said bushing is configured to allow relative axial movement between said base and said arm or relative radial movement between said base and said arm; a seal assembly sealingly positioned between said arm and said base, wherein said seal assembly is coaxial with said pivot axis and characterised in that said cover is a spring cap or a deflected arm plate and in that said seal assembly includes a primary seal having a seal body and a deflectable flange coupled to said seal body, and wherein said flange is in axial compression so that it is configured to accommodate relative axial movement between said base and said arm and relative radial movement between said base and said arm while still maintaining a seal therebetween; and a supplemental seal sealingly positioned between said arm and said cover; wherein said primary seal is positioned and configured to block external contaminants from reaching a first exposed end of said bushing and the supplemental seal is positioned and configured to block external contaminants from reaching a second, opposite exposed end of said bushing; wherein said relative axial movement causes one of said primary seal or said supplemental seal to compress and the other one of said primary seal and supplemental seal to expand. a base; an arm pivotally coupled to said base, said arm having an engagement surface and being configured to pivot relative to said base about a pivot axis; a biasing mechanism operatively coupled to said arm to bias said arm relative to said base; a bushing having a cyclindrical portion at one end of the bushing and a flange portion at the other end of the bushing, or separate bushings comprising a cylindrical bushing and a spring bushing positioned between said arm and said base; a cover fixedly coupled to said base at an axial end thereof; wherein the cylindrical portion or the cylindrical bushing is positioned radially between an inner flange of the arm and said base, thereby providing radial alignment between said arm and said base; wherein the flange portion or the flange bushing is positioned axially between an end flange of the base and a connecting portion of the arm, thereby providing axial alignment between the arm and the base; wherein sufficient wear in said bushing is configured to allow relative axial movement between said base and said arm or relative radial movement between said base and said arm; a seal assembly sealingly positioned between said arm and said base, wherein said seal assembly is coaxial with said pivot axis and characterised in that said cover is a spring cap or a deflected arm plate and in that said seal assembly includes a primary seal having a seal body and a deflectable flange coupled to said seal body, and wherein said flange is in axial compression so that it is configured to accommodate relative axial movement between said base and said arm and relative radial movement between said base and said arm while still maintaining a seal therebetween; and a supplemental seal sealingly positioned between said arm and said cover; wherein said primary seal is positioned and configured to block external contaminants from reaching a first exposed end of said bushing and the supplemental seal is positioned and configured to block external contaminants from reaching a second, opposite exposed end of said bushing; wherein said relative axial movement causes one of said primary seal or said supplemental seal to compress and the other one of said primary seal and supplemental seal to expand.