Hydro-mechanical stop having a restrictive passage

In a telescopic shock absorber including a working cylinder, a piston slideably received within said working cylinder and defining a boundary for a rebound chamber within said cylinder, a piston rod connected to said piston and extending through one end of said working cylinder means for closing said one end of said cylinder and slideably mounting said piston rod, the improvement comprising a hydro-mechanical stop characterized by:

• a resiliently flexible ring mounted about said piston rod;
• said ring having an annular outer wall with a diameter smaller than the diameter of an inner wall of said working cylinder;
• first and second collars pressed fit into opposite axial open ends of said flexible ring;
• each collar having an axial extending portion;
• said axial extending portion having an inner wall with a diameter sized to receive said piston rod with a clearance therebetween and an outer diameter sized to be pressed fit within said flexible ring;
• each collar having a radially outwardly extending shoulder, said shoulder having a surface facing axially inwardly for abutting an axial end of said flexible ring and a surface facing axially outwardly;
• said surface facing axially outwardly having a plurality of axially extending protrusions circumferentially spaced thereabout;
• said flexible ring and pressed fit collars interposed between said closure means and a shoulder fixed to said piston rod such that, at the end of a rebound stroke of said piston rod, said shoulder and said closure means axially compress said ring by pressing against said protrusions of said respective second and first collars;
• said flexible ring being sufficiently flexible such that, when it is axially compressed a predetermined amount, the diameter of an annular portion of said annular wall enlarges to abut said inner wall of said working cylinder and forming with said cylinder and said closure means a hydraulic chamber;
• the inner wall of said flexible ring spaced from said piston rod defining an annular chamber therebetween;
• said second collar, when in abutment with said shoulder fixed to said piston rod forming a second restrictive passage section between said annular chamber and said rebound chamber, said second restrictive passage section running radially between said shoulder fixed to said piston rod and said shoulder of said second collar and thence along the axial, annular space formed by the inner wall of said second collar and said piston rod;
• said first collar and said closure means, when in abutment with each other, forming a first restrictive passage section from said hydraulic chamber to said annular chamber, said first restrictive passage section running radially between said closure means and said shoulder of said first collar and thence along the axial, annular space formed by the inner wall of said first collar and said piston rod;
• and
• said first restrictive passage section restricting hydraulic fluid flow in a controlled manner from said hydraulic chamber into said annular chamber and said second restrictive passage section restricting hydraulic fluid flow in a controlled manner from said annular chamber into that portion of said rebound chamber lying between said shoulder fixed to said piston rod and said piston upon further compression of said flexible ring beyond said predetermined amount.