Patent GB-630460-A (GB)
Title: Manoeuvring gear for reversible internal-combustion engines
IPC: F01L13/02
Filed: 1947-06-17
Abstract: 630,460. Pumps ; starting ; reversing ; stopping ; valve gear. NORDBERG MANUFACTURING CO. June 17, 1947, No. 15944. Convention date, Feb. 27; 1939. [Classes 7 (iii), 7 (v) and 7 (vi)] In a manoeuvring gear for a reversible internal-combustion engine, including a fluid-pressure actuated reversing motor operable to condition the engine for forward and for reverse running and a cam mechanism operable by rotation of a control shaft in one or the other direction from a neutral position and adapted to operate a valve system for actuating said reversing motor, the shaft is rotatable through a limited engine-conditioning or " reversing range " on either side of neutral to operate the valve system, means operable by rotation of the shaft beyond the " reversing " ranges are adapted to operate the engine, and a locking mechanism is arranged to arrest rotation of the shaft at the limit of either of the " reversing ranges until the reversing motor has fully responded to the valve system when the shaft is moved to condition the engine for operation in the direction opposite to that for which it was previously set. When a control rack 12, Fig. 1, has moved by a full-downward stroke from the top position shown, it rotates a reversing crank-shaft 16 through 360 degrees by means of gears 13, 14 and 15. The uppermost position of the rack 12 sets the engine to operate in the forward direction and the lower position of the rack provides for astern or reverse running. Upon rotation of the reversing crank-shaft 16, a scroll cam 22 operates through a shifting fork and sleeve to move the engine crank-shaft 17 axially and so place under an inlet-valve push-rod 19 either a reverse cam 18r or a forward cam 18f . At the same time, a crank 29 on the reversing crank-shaft 16 laterally displaces the push rod 19 and permits the interchange of the cams. Every cylinder is provided with poppet air-starting valves 55, Fig. 5, in addition to a fuel pump 43, and each of these latter components is operated by a push rod and rocker arm, the former being laterally moved during engine reversals by aligned cranks on the reversing crank-shaft 16 so that all the push rods are operated in unison. The air-starting valve push-rods 32 only engage their cams when the starting air is turned on, under which conditions a header 53 is placed under pressure and the air from it forces up a piston 66 which through a rocker arm 59 moves the push rod into engagement with either its forward or reverse cam. The control rack 12, Fig. 1, is operated by an air-pressure motor 71, including a piston 76, which is provided with a hydraulic stabilizing-cylinder 72 and piston 77, both pistons being on a common rod connected to the control rack 12. The spaces above and below the piston 77 are normally connected through an adjustable needle-valve 79. When air under pressure is not available the control rack 12 may be operated by the hydraulic-stabilizing piston and cylinder 72, 77 by means of a hand pump 81 after closing a stop cock 84 and turning a four-way cock 83 through 45 degrees either side of the position shown in Fig. 1, depending upon the required direction of engine rotation. Cocks 83, 84 comprise a single unit. A hand-operated valve 92, Fig. 2, controls the flow of air from a pipe 91, connected to an air receiver (not shown), to a chamber 95 which feeds pipes 96, 97, the latter supplying a manifold 100. The control shaft 101, shown in the central or engine-stopped position and which is transversely located below the front end of the cam shaft 17, has a pinion 102 fixed to it that meshes with a sector 103, operated by a handle, which rotates the control shaft 101 through its complete operating range of 180 degrees. At the far end of the control shaft 101 is a cam 106, concentric with the shaft for an angle corresponding to the angle moved by the shaft between the commencement of fuel feed for forward and reverse running, which by means of its follower and a linkage system operates a rack 44, Fig. 5, through a shaft 45, that varies the point at which the spill back of the fuel-injection pumps 43 occur and hence delivery to the fuel nozzles 42 ceases. With the control shaft 101, Fig. 2, in the mid-position shown, another cam 107 causes a poppet valve 112 to close and a co-operating-poppet valve 113 to open, allowing air from the manifold 100 to pass into a brake cylinder 117 and energise a fly-wheel brake ; on either side of this position the cam 107 causes valve 113 to close and valve 112 to open and vent the brake cylinder 117 through a valve-exhaust port 118. The cylinder 117 must be vented before air is admitted to the header 53, Fig. 5. Another poppet valve 122, Fig. 2, is supplied from the manifold 100 so that when forced off its seat, air flows through pipe 124, check valve 125, pipe 126, to the top side of the air-pressure piston 76, Fig. 1, and when the valve 122, Fig. 2, is released, pipe 124 only is vented through a valveexhaust port 131. Another similar valve 132 supplies air to a pipe 134, which latter leads to a valve 141, Fig. 1, that in its upper-most position disconnects a pipe 143 from the valve-exhaust port 144 and permits air to flow through a check valve 145 to the underside of piston 76. The rate of venting through exhaust port 144 is determined by a bleed hole in the check valve 145. A latch 149 operated by the stem of valve 141 prevents undesirable anti-clockwise rotation of the reversing crankshaft 16, when that shaft is in the limiting-clockwise position, by engaging a lug 148 on a disc secured to the shaft. A cam slot 166 in the control rack 12 effects axial movement of a sleeve 154, Fig. 2, splined on the control shaft 101, through a linkage system when the control rack is operated and by means of cams 167, 168 on the sleeve operates the valves 122 or 132. The cams 167,168 are so positioned that only one valve is operated at a time, depending upon the desired direction of engine rotation and are provided with inclined portions terminating in shoulders to prevent the control shaft 101 from being moved to either of the air-starting positions until the control rack 12 and hence sleeve 154 have completed their movements. A branch from the pipe 126 leads to a poppet valve 175 which is controlled from a cam 179, the cam being so formed that the valve 175 is only opened, and so vents the pipe 126 through valve-exhaust port 177, when the control shaft 101 is in the forward-running position. The pipe 96 supplies air to a chamber above another valve 183, which latter normally allows air to enter a pipe 184. If the valve 183 is forced upwards, the pipe 184 is vented through valve-exhaust port 186. The pressure in pipe 184 acts on the lower face of a spring-loaded piston 187, its upper face being acted upon by air from the chamber 95. Connected to the piston 187 is supply valve 189 controlling communication with a chamber .191 connected to the header 53, Fig. 5, which latter is supplied with air when pipe 184, Fig. 2, is vented. A valve 193 vents the header 53, when the supply valve 189 closes so that springs 57, Fig. 5, move piston 66 downwards and draw the push rods out of engagement with their cams on cam shaft 17. Since a valve 181, Fig. 2, controls the supply of starting air for forward or reverse running it is provided with two laterallyslidable cams 197, 198 so that the valve 181 is only operated when the control shaft 101 is moved away from the mid-position. Oblique shoulders 199 on the cams co-operate with a valve follower 185 to move the cams axially when they are in the path of the follower and the control shaft 101 is being moved toward its mid-position. A lug on the frame restores the cam to its active position when the follower 185 has moved out of its path. Spring detents are used to provide against accidental displacement of the cams 197, 198. Thus for either forward or reverse direction of engine rotation the control shaft has three distinct ranges, the first providing for conditioning the engine for opposite rotation and operating an engine brake, the second affording release of the brake and air starting of the engine in the selected direction and the third providing for control of the fuel.