Gas spring with means for retaining piston adjacent one terminal position

In a cylinder-and-piston device including (a) a cylinder having an axis and defining a sealed cavity therein;

• (b) at least one fluid in said cavity;
• (c) a piston assembly axially movable in said cavity towards and away from a terminal position, and including (1) a piston axially dividing said cavity into first and second compartments, (2) means defining a first passage extending axially across said piston for connecting said first and second compartments when said piston assembly is remote from said terminal position, (3) a piston rod fastened to said piston for joint movement therewith and extending from the piston through said first compartment and axially outward of said cavity, (4) means defining a second passage extending axially across said piston for connecting said first and second compartments, and (5) valve means for closing said second passage in response to movement of said piston assembly away from said terminal position and for opening said second passage in response to movement of said piston assembly towards said terminal position;
• and (d) locking means in said cavity for closing said first passage when said piston assembly approaches said terminal position, the improvement in said locking means comprising:
• means carried by and axially movable with said piston assembly along substantially the total stroke of said piston assembly towards and away from said terminal position defining an opening to said first passage which is directed towards that end of the cylinder which is nearer to said piston assembly when said piston assembly is in said terminal position;
• sealing means located within said cylinder on that side of the piston assembly nearer to said terminal position in substantial axial alignment with said opening;
• and
• means for axially resiliently supporting at least one of said opening-defining means with respect to said piston assembly and said sealing means with respect to said cylinder such that said sealing means abuts said opening under the action of said resilient means to close said first passage when said piston assembly approaches said terminal position, wherein once said first passage has been closed and said piston assembly is adjacent said terminal position a pressure difference between said first and second compartments results when said piston assembly begins to move away from said terminal position, said pressure difference thereby retaining said piston assembly adjacent said terminal position.