Hydraulic shock absorber and pneumatic spring device

Claim 1

In a fender shock absorber of the type provided with an outer tube having a liquidtight closure at one end thereof and supported to extend horizontally, a likewise horizontally extending inner tube telescopically engaging said outer tube through the other end thereof and having an inner terminal section located inside said outer tube opposite said closure to define therewith and with the wall of said outer tube a variablevolume plenum filled with hydraulic liquid, and an outer terminal section projecting outside said outer tube and sealed to define with said inner terminal section and the wall of said inner tube a constant-volume pneumatic spring chamber containing an underlying amount of hydraulic liquid at a lowermost region thereof and an overtopping amount of gas under pressure above the liquid level therein, locking means associated with said sealed outer terminal section for securing said inner tube against angular displacement about the axis thereof thereby angularly locating said lowermost region of said pneumatic spring chamber, the improvement comprising a liquid flow control mechanism fitted at said inner terminal section of said horizontally extending inner tube, said control mechanism comprising the combination of: a plug secured to the extremity of said inner terminal section, a transverse partition secured to said inner terminal section in axially spaced relationship with said plug towards the outer terminal section of said inner tube to define with said plug a chamber intermediate said variable-volume plenum and said constant-volume pneumatic spring chamber, a first constricted passageway connecting said plenum with said intermediate chamber and permanently allowing liquid flow in both directions while offering resistance thereto, a second constricted passageway connecting said intermediate chamber with said lowermost region below said liquid level in said pneumatic spring chamber and permanently allowing liquid flow in both directions while offering resistance thereto, a third passageway formed through said partition to connect said intermediate chamber with said pneumatic spring chamber in spaced parallel flow relationship with said second constricted passageway, said third passageway having a passage area substantially larger than that of said second constricted passageway, and a check valve associated with said third passageway to permit flow therethrough from said intermediate chamber towards said pneumatic spring chamber upon plunging movement of said inner tube into said outer tube, while hindering flow in the opposite direction upon extension movement of said inNer tube out of said outer tube.