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).
Article from 'Automotive Industries' detailing the features of an engine, including its valve timing, fuel vaporizer, and lubrication system.
Identifier | ExFiles\Box 50\3\ Scan051 | |
Date | 6th January 1921 | |
6 AUTOMOTIVE INDUSTRIES THE AUTOMOBILE January 6, 1921 completely inclosed, and the breather is located in the pressed steel valve cover on the top of the cylinder head. This insures a plentiful supply of oil to the valve rocker arms and the cup in the rocker arm is always full of oil. Valve clearance can be adjusted while the engine is running, which is said to be a great convenience. A conventional three-bearing camshaft is used. The valve timing is as follows: Exhaust closes and intake opens at 10 deg. past top dead center; exhaust opens 50 deg. ahead of bottom dead center and intake closes 57 deg. after bottom dead center. The front bearing does not support the camshaft directly, but through a sleeve which carries the ignition distributor gear at its rear end and a flange at the front end. To the latter the camshaft gear is secured with four cap screws. End play is taken up at the forward end by a phosphor bronze thrust washer, which can be adjusted by a set screw in the timing gear cover. The flange on the camshaft collar takes the thrust in the other direction against the camshaft bushing. The Fuel Vaporizer A horizontal Rayfield carbureter is bolted to the combined intake and exhaust manifold on the right side of the engine. The mixture leaving the carbureter strikes a series of ribs that are heated by the exhaust and are directly in line with the incoming mixture. The mixture is deflected upward over them by the shape of the manifold and because of this change in direction, the heavier particles of unvaporized gas are thrown out of the mixture and precipitated on the ribs where the heat of the exhaust vaporizes them. The intake manifold measures 1¾ in. in diameter at all sections, hence the gas velocity is not sufficient to sweep unvaporized particles of the fuel off of the vaporizing ribs. The use of separate exhaust pipes and mufflers for each group of three cylinders prevents the overlapping exhaust from interfering. One of the features of the lubricating system is the control of oil pressure by vacuum. When the throttle is nearly closed and the engine is running light but little lubricant is needed. At such times there is a high vacuum in the intake manifold and the vacuum operated piston controlling the oil by-pass valve is raised against spring pressure, thus opening the oil by-pass. The oil pressure is thereby reduced and excessive oiling and smoking are prevented. The oil pressure regulator is located at the front end of the crankcase immediately over the oil groove in the front main bearing into which the oil passing through the crankshaft is discharged. The plunger, which acts as a valve, extends down into the crankcase to the bearing groove. The piston is located in a small cylinder casting on the outside of the case. This cylinder is connected to the intake manifold. The system operates at a maximum pressure of 40 lb. per sq. in. The oil level in the crankcase is determined by means of a bayonet type gage. A Rayfield regulator is used for the thermostatic control of the cooling system. The water is circulated by a new type of screw or turbo-impeller pump which gives a good head of water at low speeds and yet does not give excessive circulation at high speeds. The pump is open so that thermal circulation takes place if the pump drive fails. The pump is located at the rear end of the engine and is driven through the electric generator and a small shaft with two fabric universal joints. The water enters the cylinder jacket through a distributor pipe with three outlets, the object being to assure uniform distribution of water with consequent uniform cylinder temperature. The use of only two timing gears and belt drives for the auxiliary apparatus is quite a departure from con-ventional-practice. It has been found that two gears with 1.25-in. face and a spiral angle of nearly 24 deg. can be made from steel and iron and kept quiet if a third gear is not meshed with them. The gears are rough hobbed and then finished on a Fellows helical gear shaper. The fan, generator and water pump are driven by Graton & Knight 28 deg. V link belts. There are two independent belt drives, one for the fan and the other for the generator. The fan is mounted on an adjustable support, and adjustment for the generator drive is provided for by using a standard S. A. {Mr Adams} E. {Mr Elliott - Chief Engineer} mounting for the electric generator, whereby the generator can be swung through quite an arc. This feature makes necessary the two universal joints between generator and water pump. The new Ansted engine is combined with a transmission forming a unit powerplant and has a new design of multiple disk clutch which is now being made by the Lexington company. It contains five driving and six driven disks. There are ten floating Raybestos moulded friction rings in between the metal disks of saw steel. The Raybestos disks just clear the driven clutch drum so that when the clutch is released they cannot drop in the teeth of the driving member. Teeth of 10-12 pit. are cut on the inside of the driving and on the outside of the driven clutch members. The teeth on the clutch plates and the drums are formed on a Fellows gear shaper. The most marked change in the chassis is the lengthening of the frame to give a 128-in. wheelbase in place of 120-in. The section of the side frame channel is now practically 9 in. in depth with 2-in. flanges, top and bot- Transverse section of Ansted engine, showing "rocking chair" type of rocker arm used to in-crease and decrease valve acceleration in opening and closing | ||