GB696168A - Improvements relating to double-acting pneumatic pumps - Google Patents

Abstract

696,168. Pistons; stuffing-boxes. BOTHE, O. July 27, 1951, No. 17840/51. Classes 122(i) and 122(v) [Also in Group XXVIII] A double-acting air pump, especially for inflating pneumatic tyres, comprises a cylinder 1 provided with a slip-over handle 7 and a hollow pistonrod 5 carrying a double-acting piston 6 formed by a pair of cups which enclose a pressure chamber communicating through the hollow piston -rod with an outlet nipple 8, leakage between the piston rod. and cylinder being prevented'by a flexible annular disc, 20a, Fig. 4a, which forms the sealing member of a stuffing box. Inlet ports, such as 19, controlled by flexible discs, such as the disc 20a, are provided in the cylinder end caps 3, 4. The piston, Fig. 6, has a pair of rubber cups 29, 30 pressed apart by a spring 33 and each controlling transfer ports 35. In another embodiment, Fig. 8, two flexible discs 41, 42, initially flat, are deformed by the cylinder 1 to form cups and are pressed apart by a ring 45 which divides the pressure chamber 46 from a chamber 49 adapted to be filled with lubricant and which may also contain lubricant absorbent material. Other embodiments of the piston are described in which the cups are directed outwardly and in which the lubricant chamber is on one side of the piston. The outlet nipple 8, Fig. 5a, has a rubber sleeve member 26 adapted to receive the tyre valve 27. A pressure release valve 28 is provided to facilitate the removal of the tyre valve. The cylinder 1 is covered with a tube of rubber or the like which forms a hand grip and the bore of the cylinder may be enlarged at one end in order to allow the piston cups to relax when the pump is in the rest position. The enlargement may have axial grooves to facilitate the filling of the lubricant chamber from outside.