Door control device

A door control device comprising a hollow housing defining a chamber and a piston disposed in the chamber and capable of reciprocal movement relative to the housing along a rectilinear path, the door control device further comprising an elongate flow control element which extends into the piston, the piston having a face which is transverse to said path, said face having an aperture spaced from the housing, the piston comprising a seal with a radially outer portion which engages the housing in sliding contact therewith to seal the interface between the piston and the housing and a radially inner portion which slidably engages the elongated flow control element and wherein the seal also includes a relatively flexible intermediate portion overlapping said face of the piston, which intermediate portion seals the aperture in the piston when the piston is subjected to hydraulic pressure acting in a first direction along the path of travel of the piston and wherein the face of the piston provides a seat for said flexible portion of the seal and said flexible portion can flex away from the seat when subjected to hydraulic pressure acting in a second direction along said path.