Shock absorber construction

A shock absorber comprising a casing having first and second ends, a chamber in said casing for containing fluid, a piston head in said chamber, a piston rod mounting said piston head and extending through said first end, means at said first end of said casing for supporting said piston rod for sliding movement, bleed means in said casing for providing said fluid to said chamber from an area external of said casing, reversible check valve means mountable in first and second positions on said casing for causing said shock absorber to provide shock absorption in a first direction of piston movement when said check valve means is in said first position and for causing said shock absorber to provide shock absorption in a second direction which is opposite to said first direction when said check valve means is in said second position, said check valve means comprising a cartridge, said cartridge comprising an elongated housing having first and second housing ends, a housing orifice in said first end, a check valve member, an elongated spring extending between said check valve member and said second housing end for biasing said check valve member toward said housing orifice in said first housing end, means at said second end of said casing for mounting said cartridge, an end wall at said second end of said casing, a bore in said end wall, an opening in said second housing end, spring pressing means mounted in said opening in said second housing end for bearing on the end of said spring remote from said check valve member, retaining means for retaining said cartridge in said bore in said second end wall, said spring pressing means comprising a presser member extending through said opening in said second housing end, a first end on said presser member for engaging said spring, and a second end on said presser member for receiving a force for effecting movement of said presser member into said cartridge for compressing said spring.