Hydropneumatic shock absorbing mounted bumper

A shock absorbing arrangement comprising:

• a. a vehicle having a chassis and a wheel mounted on said chassis for permitting said vehicle to roll on a horizontal surface in a predetermined direction;
• b. a bumper;
• c. a shock absorber securing said bumper to said chassis in a position in which said bumper projects from said chassis in said direction, said shock absorber including:
• 1, a cylinder member having an approximately horizontal axis and a cavity closed at one axial end;
• 2. a hollow piston assembly movable axially relative to said cylinder inward and outward of said cavity, said assembly including
• i. a piston sealingly engaging said cylinder member while said assembly moves, and
• ii. a piston rod member fixedly fastened to said piston and axially projecting from the other axial end of said cavity, said members being fastened to said chassis and said bumper respectively;
• 3. stroke limiting means for preventing said assembly from moving axially beyond a first innermost position and beyond a second outermost position relative to said cavity;
• 4. a first body of liquid substantially completely filling the axial portion of said cavity between said piston and the closed axial end of said cavity;
• 5. a second body of liquid in the hollow interior of said assembly;
• 6. conduit means defining a permanently open throttling passage connecting said first and second bodies and having respective orifices in said cavity and in said interior,
• i. said conduit means including an integral wall of annular cross section bounding said orifices and connecting the same,
• ii. the flow section of said passage being constant during axial movement of said assembly between said first and second positions;
• and
• 7. a body of gas sealed in said interior in pressure-transmitting relationship with said second body,
• i. whereby said assembly is moved axially inward of said cavity by abutting engagement of said bumper with a fixed obstacle when said vehicle collides with said obstacle while rolling on said surface under the inertia therof, the velocity of said inward movement is decreased from an initial value by a resistance having a first component due to the throttling effect of said passage on the flow of said liquid and a second component due to the compression of said gas, and said inward movement is arrested in a terminal position of said assembly before the assembly reaches said first position when said initial value does not exceed a predetermined magnitude, said first component decreasing with the decreasing velocity of said assembly, and said second component increasing due to said assembly approaching said first position,
• ii. the amount and pressure of said gas being sufficient to make said resistance in said terminal position approximately equal to said resistance at said predetermined magnitude of said velocity, and sufficient to move said assembly from said terminal position into said second position in the absence of applied external forces.