Patent GB-1161105-A (GB)
Title: Hydraulic System for Boats for Controlling and Actuating a Tiltable Outboard Propeller Shaft Housing.
IPC: B63H20/22
Filed: 1967-01-26
Abstract: 1,161,105. Marine craft; outboard drives. VOLVAPENTA A.B. 26 Jan., 1967 [8 Feb., 1966], No. 3887/67. Heading B7V. [Also in Division F1] A marine propeller-driving mechanism includes a gear-box 3, Fig. 1, attached to the stern-board 56 of a boat (not shown) and containing the upper end of a propeller-shaft housing 7 that is supported by a horizontal pivot 6, Fig. 3, so that it can be displaced angularly in a vertical direction by an hydraulic double-acting piston-and-cylinder unit 5 as required, the latter being controlled by an hydraulic-fluid distribution device 4 contrived such that when the housing 7 meets an obstacle while the boat is moving ahead it is free to rotate upwardly about the pivot aforesaid and, when the boat is driven astern, the piston 51 in the unit 5 can be locked to prevent upward rotation of the housing by the action of the propeller. The unit 5 is pivotally connected to the housing 7 by a link 54 and is hydraulically connected in parallel with a single-acting piston-and-cylinder unit 8 that serves to trim the angular position of the housing, the latter unit being furnished with a piston-rod 59 that carries a plate 60 having a pad 62 thereon that abuts a portion 61 of the housing. Hydraulic connection between the units 5 and 8 is effected by a pipe 63 coupled to a pipe 43 that connects the uppermost working-chamber 44 of the unit 5 to a passage 42, Fig. 3, on the outlet side of an hydraulic-fluid distribution-device 4 attached to the gear-box 3. An inlet passage 27 in the device aforesaid receives pressurized hydraulicfluid, e.g. oil, from a pump 2 containing a piston 11 that is driven by an eccentric 9 on the driving shaft 1 of an in-board motor (not shown), the piston being slidingly lodged within a tubular sleeve 13 that is engaged by the eccentric through a compression-spring 15 against the action of a further compressionspring 16 abutting a piston 14 on the uppermost end of the sleeve. The uppermost end of a pumping chamber 20 is defined by a hollow plug 21 containing a ball valve member 23. In operation of the pump, an inlet port 24 in said sleeve is closed by the piston when the latter travels upwardly while the sleeve is held stationary by the spring 16, fluid being driven past the valve-member 23 through a port 26 in the sleeve into the passage 27. When a pre-determined pressure is reached at the port 26 the piston 14 is forced upwardly so as to reopen the port 24 and prevent a further rise in pressure. The device 4 includes a slidable tubularsleeve 31 having land 41 thereon that controls the passage 27, the sleeve being movable by manual actuation of a lever 37 that abuts a rod 32 whose lowermost end is in contact with a cam 33 attached to the housing 7. The lever 37 is operated by a Bowden cable (36), Fig. 6 (not shown), the sheath of which cable is attached to a bracket (35) that is carried by a holder 34 therefor on the sleeve 31, whereby tension applied to the cable results in upward displacement of the sleeve and connection of the passage 27 to the units 5, 8 through the passage 42 and the pipe 43. When the chamber 44 in the unit 5 is thus charged with pressurized fluid, the chamber 47 on the opposite side of the piston 51 is connected to a sump (not shown) through a pipe 46, a rotatable valve-member 48, a passage 50 and a conduit 30, and consequently the housing 7 is rotated upwardly. The area of the piston 58 in the unit 8 is greater than that of the piston 51 so that by appropriate operation of the lever 37 trimming of the position of the propeller can be effected while the unit 5 remains substantially inoperative. When the sleeve is moved downwardly from the position shown by suitable movement of the lever 37, the chamber 47 is charged with pressurized fluid while the chamber 44 is connected to the sump through a passage 49 so that the housing 7 is rotated downwardly. Closure of the valve 48 while the propeller is being operated to drive the boat astern prevents fluid escaping from the chamber 47 and the housing from moving upwardly. When the valve 48 is open and the sleeve 31 is kept in the position shown such that fluid is held under pressure in the chambers 44, 47 to prevent displacement of the housing in either direction, fluid can escape from the chamber 47 past an adjustable valvemember 64 into the conduit 30, and hence to the sump, whenever the housing encounters an obstruction.