Hydraulic gear pumps or motors

1,137,566. Rotary pumps and motors. KIROVOGRADSKY AGREGATNY ZAVOD. Sept. 20, 1966, No.41963/66. Heading F1F. A rotary hydraulic pump, or motor, of the externally-meshing gear type comprises a pair of blocks or inserts 3, 4 that together constitute bearings for shafts 8, 9, which are rendered integral with the gears, the insert 3 being furnished with arcuate faces 44 adjacent the gearteeth and pressed towards the latter by the liquid in an inlet or outlet passage 29 on the high-pressure side of the gears to minimize leakage across the tips of the gear-teeth. Leakage across the end faces of the gears in minimized by a pair of plates 10 being pressed axially inwards by pressure communicated to grooves 18 in their axiallyoutermost faces from the high-pressure side of the gears through ducts 22, the grooves 18 being provided with sealing elements or cups 18 and connected to grooves 14 in the insert 3 containing sealing cups 15 by ducts 45, 46. Further sealing cups 21 in the plate 10 are pressed against the insert 3 by pressure communicated thereto from the high-pressure side of the gears through ducts (not shown). A proportion of the liquid flowing to or from an inlet or outlet passage 23 on lowpressure side of the gears enters a gap 43 between the inserts through ducts 26, 27 to effect cooling and lubrication of the shafts 8, 9. Leakage of liquid from the passage 29 to the low-pressure side of the gears is prevented by a sealing cup 17.