Abstract: The external seal is mounted on a housing about a rotary shaft projecting through an opening in the housing. The seal is a resilient, flexible member having a generally tubular body portion with an annular lip extending radially outwardly from one end of the body portion and a flange extending radially outwardly from the other end of the body portion. The lip extends into a sealing chamber formed by the outside of the housing and a replaceable sealing member which has an inside surface spaced from and parallel to the outside of the housing. The tubular portion of the seal extends through an annulus formed by the shaft and the replaceable member. The outwardly extending flange is used to prevent the clamp holding the seal to the shaft from falling out.