993,812. Hydro-pneumatic shock absorbers. USTAV PRO VYZKUM MOTOROVYCH VOZIDEL. April 18, 1963 [April 25, 1962], No. 15302/63. Heading F2S. [Also in Division B7] A self-levelling hydro-pneumatic suspension unit 24 is provided with a charging valve 15 containing a piston 16 with an annular groove 17 which, in the position shown, connects a pressure liquid supply line 14 with line 19 and the suspension unit 24 to charge the unit increasing its length until groove 25 communicates with chamber 26 of the unit 24 when pressure fluid passes through line 8 to the space below piston 16 raising the piston against spring 18 and cutting-off the supply conduit. A bleed hole 20 connects the space above piston 16 with atmosphere. When charging is complete, line 14 may be connected to a reservoir when the fluid in the space below the piston 16 will be pushed by spring 18 past non-return valve 22 and through line 14 to the reservoir. In a modification the charging valve is mounted on the unit 24.