Cylinder cushion seal

A cushion seal for an expansible chamber motor comprising an annular body of elastomeric material having an axis, an inner bore, a circumference, a first radial face and a second radial face, said faces defining the seal body axial dimension and said bore and circumference defining the seal body radial dimension, said body being of a solid construction through said axial and radial dimensions, said bore including a conical surface having a minimum diameter in the direction of said body first face and a maximum dimension adjacent said second face, at least one radial channel defined in said first face intersecting said bore and said circumference, at least one axially extending channel defined in said circumference intersecting said first and second faces, said radial and axial channels being in communication adjacent said body circumference.