Patent ID: 8342304

Claim:
A pneumatic retarding device ( 10 ) comprising a cylinder ( 21 ) having a smooth inner wall, a piston ( 51 ) with a piston rod ( 42 ) movably disposed in the cylinder ( 21 ), the piston ( 51 ) dividing the cylinder ( 21 ) into a displacement chamber ( 15 ) and a compensation chamber ( 16 ) and being provided with a piston seal element ( 71 ) for sealingly separating the displacement and compensation chambers ( 15 , 16 ) so that movement of the piston into the displacement chamber ( 15 ) causes compression of air in the displacement chamber ( 15 ) and generates a counterforce opposing movement of the piston ( 51 ) into the displacement chamber ( 15 ), and means permitting a controlled air leakage flow past the piston ( 51 ) out of the displacement chamber ( 15 ) for damping movement of the piston into the displacement chamber, the piston ( 31 ) and the piston rod ( 42 ) being a one-part piston unit ( 41 ), with the piston seal element ( 71 ) accommodated on the piston ( 51 ) comprising two deformation zones ( 73 , 74 ), a first rapidly responding deformation zone ( 73 ) which is in contact with the smooth inner wall ( 23 ) of the cylinder ( 21 ) when the retarding device is expanded and the piston ( 51 ) is in a retracted end position, and a second deformation zone ( 74 ) formed by the seal element ( 71 ) which reacts slower to a pressure generated in the displacement chamber ( 15 ) upon movement of the piston ( 51 ) into the displacement chamber ( 15 ) than the first deformation zone, the seal sleeve element ( 71 ) being a sleeve having an outer surface arranged in spaced relationship from the inner cylinder wail ( 23 ) and enclosing an inner pressure chamber ( 17 ) in communication with the displacement chamber ( 15 ) via a throttling passage permitting pressurization of the pressure chamber ( 17 ) for expanding the sleeve ( 74 ) into braking engagement with the inner cylinder wall ( 23 ) while contracting axially, the piston seal element ( 71 ) being supported on the piston ( 51 ) via a support ring ( 75 ) by a truncated conical surface area ( 55 ) of the piston ( 51 ) which is arranged between the two expansion zones ( 73 , 74 ) and whose diameter increases with increasing distance from the displacement chamber ( 15 ).