From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Instruction leaflet for the 'Orkan' universal carburetor, type U, detailing its working, fitting, adjustment, and operation.
| Identifier | ExFiles\Box 122\4\ scan0042 | |
| Date | 11th September 1927 guessed | |
| ORKAN SCHEME OF THROTTLE WORKING fig. 1, fig. 2, fig. 3, fig. 4 WORKING The fuel enters the nipple 24 through the supply tube, flows through hollow nipple-screw 23 and the calibrated hole, entering finally the float chamber 22, an uniform level being maintained here by the action of float 28, float lever 18, and float nozzle 21. Then it flows through inlet 25 into the cylindric ascension tube 26 and the annular chamber round that tube, mounting to the level in the float chamber. By the suction of the motor it is lifted to nozzle 19 and mixed there with the first quantity of supplementary air entering through that nozzle, the resulting mixture entering either elbow 14 through the holes leading thither, or the throttle axle 10, flowing directly in the sense of the nozzle-axle. When the engine is running slowly (fig. 1) the above described mixture, determined in its quantity by the position of the stem for running light, will flow through the motor side opening for running light a), having been mixed before with a second quantity of air flowing through the slits of the throttle. When the throttle is a little open (fig. 2) the mixture is divided into two parts before the nozzle. One part provides the device for running light in the above described way, whilst the other is flowing through the chief hole of the crossed part into the throttle axle, passing through a hole of the axle and of throttle 8 rightangular to the former, streaming alongside the slits, taking, from thence, another quantity of fresher air, and finally entering the first slit. The latter pours the again atomized spray of mixture into the air passing in high speed. The admission of fresh air has diminished according to the failing section of the first slit, the richness of the mixture increasing accordingly. By progressive opening of the throttle (fig. 3) more and more slits share in the supply of spray, according to the section of the opening. The mixture for the charge of the motor increases in quantity and richness, less fresh air entering through the slits. By the perfect opening of the throttle (fig. 4) all slits are engaged by the suction of the motor and supply mixture only. The fuel level in the ascension tube, and consequently in the surrounding chamber, has fallen in the meantime, because of the limited supply of the fuel inlet, so that the opening of the ascension tube becomes uncovered. The tube communicating now with the atmosphere the fuel coming from the fuel inlet receives an even quantity of fresh air through the hole of the tube, the air acting as brake air. The regulation of the quantity of air passing besides the throttle, and consequently of the charge of the motor, is operated by putting and adequate air tube 1 before the throttle pipe. FITTING UP THE CARBURETOR 1. The „Orkan“ universal carburetor is to be flanged to the motor directly by a heat-interchanging packing, so that the float chamber is situated vertically, before the throttle pipe (in the direction of motion.) 2. An efficacious filter is to be inserted into the fuel supply pipe, the filter may be delivered together with the carburetor. The supply pipe should be as short as possible and without vertical loops. 3. The gas gear should have no lost motion, and should give way to the whole turn of the throttle. 4. For the operation of the stem for running light a suitable Bowden wire is to be placed near the hands of the driver. 5. The fuel level should mount to the bottom of the seating of the crossed part, in the float, but not more than 2 mm above that point. The designation of the employed fuel must be seen on the float lever. 6. A shoulder on the carburetor-flange is provided for the application of the vacuum tube, if a vacuum apparatus is employed. ADJUSTMENT OF THE CARBURETOR It consists essentially in finding the suitable air tube, fuel inlet, and ascension tube. The section of the fuel inlet may be found together with that of the air tube when the motor is performing its maximum power. The size of the ascension tube, influencing specially the consumption at high speed, may be determined afterwards. The largest size possible should be applied. The device for running light is adjustable by means of the crusted nut screwed on the end of the throttle axle. By screwing off the nut, the passage for the mixture, checked by the stem for running light, grows larger, the supply of the running-light device becomes richer. The position for running light of the throttle may be determined by the stop screw. START AND OPERATION When starting the cold motor pull the Bowden wire of the device for running light; a very rich mixture will be supplied into the suction tube of the motor. When the motor is running slowly release the Bowden wire, until the stem be in its normal place. An eventual choking of the device for running light will be cleaned away by that operation. » ORKAN « UNIVERSAL CARBURETOR TYPE „U” Sueddeutsche Bremsen-A.{Mr Adams}-G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Muenchen 46 (Germany) EINLAGE No 969 | ||