The action is as follows. When the engine is on the impulse stroke, the ignition valve F is full open, and all the other valves closed. The roller on the exhaust lever is put in the position to gear with the relief cam, the gas supply is turned on slightly, so as to fill the gas bag, the escape valve A is opened by placing the small lever B in the notches marked 'To start,' the valve C' is opened, and the gas coming in under pressure drives out a portion of the air inside the combustion chamber. The only aperture by which the air can escape is in the direction of the arrows by passing the timing valve, and then up the central ignition tube and down the space between inner and outer tubes-which is heated to incandescence-and SCALEGO FIG. 132. STARTING DIAGRAM-- STOCKPORT through the valve A to the atmosphere. In one minute this gas is in sufficient quantity to form an ignitible mixture; the velocity is such that the charge is fired by the ignition tube. After the engine has made about six explosions (see fig. 132) the valves A', B, and C' must be closed, the gas cock on the gas bag opened full, the exhaust roller on the exhaust lever be moved so that it comes into gear with the main exhaust cam, and the engine will be in full working order. This starter is simple and effective. Norris's Starter Fig. 133 (No. 4) is a facsimile of a diagram taken from an 18 B.H.P. Robey engine fitted with the author's 'impulse every Κ revolution starter' in 1891. In this arrangement a double set of cams are necessary so that the engine has an impulse every revolution, until sufficient speed has been attained to fire with it from the tube; a pilot light is arranged at the back in close proximity to a small touch-hole. SCALE 64 FIG. 133.-STARTING DIAGRAM-NORRIS To start the engine the pilot light is lit, the touch-hole opened, the flywheel moved by hand or lever, and gas and air is drawn in for about one-third of the stroke, the flame is drawn into the cylinder through the touch-hole, and an impulse is given; on the return stroke the products of combustion are expelled. The next forward stroke gas and air is drawn in and another impulse given which is continued until sufficient velocity has been attained to start in the ordinary way. It makes little or no difference if the touch-hole is closed with a spindle or not. The amount of explosion escaping is practically nil. The complication necessary in using this method prohibits its use. Clerk-Lanchester High-pressure Starter In 1891 Mr. Dugald Clerk invented a high-pressure starter, and used the Lanchester igniter in conjunction with it. Fig. 134 (No. 5) is a sectional elevation of the starter, showing its connection to the combustion chamber of a Robey engine having a cylinder 14 × 21 inches stroke. Fig. 135 is a diagram taken from this engine, showing a maximum pressure of 200 lbs. above the atmosphere, and an average pressure of 38.3 lbs. per square inch. To start the engine the check valve A is released and the crank is placed slightly on the firing stroke (say 11⁄2 inch), the pilot light B for the Lanchester igniter is lighted, and the gas cock C opened, the gas mingles with the air in the cylindrical chamber D and combustion chamber E, and flows out through the valve F, and as soon as an explosive mixture is formed, which is in about fifteen seconds, the roaring of the burning mixture at G indicates that the charge in the cylinder is of the right mixture. The gas cock C is shut off, and the flame shoots back and closes the small valve F. The flame so produced under atmospheric pressure fills the chamber D, and forces the gas past the check valve A into the combustion chamber, and compresses the charge to 30 lbs. per square inch, and then explodes. The mixture is therefore compressed into the combustion chamber by a preliminary explosion. To prevent the starting impulse bursting the ignition tube-when worn, or when using a porcelain tube-the igniter is thrown out of gear until the engine has received the full force of the starting inpulse. SCALE 160 FIG. 135.-STARTING DIAGRAM-CLERK-LANCHESTER It is possible to vary the force of the starting impulse by arranging the length of the connected pipe, so that a less violent explosion may be obtained. It is also possible to time the colour of the mixture issuing from G, so that the preliminary impulse puts the engine into motion previous to the main impulse being given. When the check valve A is left closed through carelessness, the greatest possible pressure obtainable is only 30 lbs. per square inch. The gas required for starting impulse = 700 cubic inches = 2,732 Capacity of the combustion chamber = 1,628 This starter is now the exclusive right of Messrs. Crossley Brothers, and is used with a long horizontal pipe, and hand pump to charge, the starting impulse being less powerful than the above. Fielding's Starter Fig. 136 (No. 6) is a sectional elevation of a 100 I.H.P. Fielding engine, fitted with starting gear, but without the air chamber, which may be fixed in any convenient position. 38.6 average Fig. 137 is a facsimile of a starting diagram taken from a 12 H.P. NOM. Fielding engine. Fig. 138 is an external end elevation showing the air reservoir A fitted with a hand pump, FIG. 136.-100 I.H.P. FIELDING ENGINE, SHOWING STARTING GEAR which is used for charging the reservoir with air at 60 lbs. per square inch when starting the engine for the first time. In this method of starting compressed air is stored in a reservoir, by the action of the engine, at about 60 lbs. per square inch, the crank is placed at an angle of 15°, one of the valves is opened by a lever, the gas being admitted much in the same STROKE 290 lbs. FIG. 137. STARTING DIAGRAM FROM 12 H.P. NOM. FIELDING ENGINE Scale, 150 lbs. per square inch. Average pressure, 99.5 lbs. per square inch manner as in the Lanchester starter; on entering, the gas is directed downwards so as to drive out the air, which escapes by the igniting port, a light is applied at the end, and the presence |