Improvements relating to pressure-loaded reservoirs and charging devices therefor

797,296. Hydraulic apparatus. DOWTY EQUIPMENT, Ltd. Oct. 5, 1956 [Oct. 6, 1955], No. 28525/55. Class 69 (2). A pressurized reservoir for an aircraft hydraulic system comprises a reservoir chamber 16 containing a piston 13 connected to a piston 20 of smaller area working in a cylinder 22 which is telescopically mounted in a cylinder 19. This arrangement enables the length of cylinder 19 to be less than the total stroke of piston 13. Chamber 16 is connected to the inlet of a pump 52 and the discharge side of the pump is in communication with the cylinder 19 through a line 58 so that the liquid in chamber 16 is pressurized. The chamber 16 is provided with an air vent float valve which closes automatically if the reservoir is inverted. For charging and replenishing the reservoir a hand pump is coupled to an inlet 60 of a charging valve 59, and liquid is pumped into valve 59 whence it passes through a valve 66 into cylinders 19, 22, moving piston 13 through its full stroke and expelling air from the chamber 16 through the float valve. At the end of the stroke, pressure builds up until a relief valve 64 is opened, whereupon liquid enters chamber 16. Liquid is then expelled from cylinders 19, 20, and passes through valves 66, 64, to the chamber 16. A plunger 46 engageable by the piston 13 indicates when the chamber 16 is full. A glass 45 allows visual observation of the liquid level.