ABOUT GAS ENGINES.

Globe, Volume IX, Issue 1265, 8 April 1878, Page 3

ABOUT GAS ENGINES.

[from the press.] The introduction into our manufactories and other places requiring motive power of a new, economical and effective engine is an important step in our history. A few particulars, therefore, concerning the recently imported gas engines may not bo uninteresting. The agent in Christchurch for the patentees, Messrs Crossley Bros., is Mr R. C. Bishop, and he has recently imported two engines, which are engaged in such totally different work as to afford a very good test of their adaptability to any machinery where motive power is required. The first one is working in Messrs Suckling and Co.’s boot factory, and is one-horse power, the other is used as a hoisting engine in Mr C. W. Turner’s large store and is two horse. It may be noted that the firm supply engines from a quarter-horse power up to three, one of the former being in use at a printing establishment hero and doing excellent work. Prior to speaking of the work done by these engines we will briefly describe the principle of the atmospheric gas engines, their advantages, and the cost of working them. First, then, as to the principle. To look at outwardly, the engine resembles a column boiled firmly to the ground. The fly-wheel and driving pulley are close together at one end of the shaft, while to the other is attached the side valve rod. Between the cylinder and the outer case of the engine a current of water is continually passing in order to absorb the heat. In running the motion of the fly-wheel is sufficient to lift the piston slightly, and a mild explosive compound of gas and air mixed is drawn in under the piston, which slides airtight in a vertical cylinder open at the top. The proportion of gas and air we may say is 3to 1. So soon as the charge is thus complete, the valve drops sufficiently to allow of the compound igniting at a small jet of gas plat ed just in front of the pipe. On igniting the charge the piston is thrown by the explosion freely to the top. As it ascends, owing to the condensation of the gases, a partial vacuum is caused, and the motion of the piston is chai ged to a down stroke, the pressure being about 111 b. to the square inch by the atmosphere. This communicates through a rack and toothed wheel to the shaft, and supplies the driving power. When the piston has reached within a given disianc • of the bottom the vacuum, which has been gtalually decreasing, cease-, and the weight of the piston and rack expels the bur> t gases in the last few inches of the strode, and is ready again for the entrance of the explosive compound. In order to connect the piston rod rack with the driving shaft there is a pulley keyed on the shaft, and surrounded by a ring, on the interior of which are cut three inclined surfaces. On each of these inclined surfaces a set of rollers is free to travel and to press against a corresponding curved wedge, whilst the p ston is descending, at the same lime the opposite side of the wedge, which is faced wiih leather, presses against the pulley. While the piston is ascending no pressure is put on these wedges by the ring, and hence in its up stroke the ring can revolve freely backwards and forwards upon its bearings on the shaft, but so soon as the dawn stroke commences a firm hold of the shaft is immediately gained by the ring, and the shaft thereby becomes connected directly with the toothed wheel which gears with the piston rod rack. The engine has attached to it a ball governor, which is one of the most importa t parts of the machinery. Without the govt-rnor the engine would go on making explosions, and using gas without doing more than run itself. The effect of the governor may be explained thus. Of course at times the machines which are run by the engine, do not demand its full power, whilst at other times they do. If the work to be done demands the full power the governor will do nothing to stop the motion of the valve gear, and explosions will take place rapidly, When, however, the work to be done reduces, the speed increases, and the governor holds a pawl so that no further supply of gas and air can enter the cylinder, no action of the valve can take place, and no explosion can drive up the piston until the speed, having fallen by the work being resumed, the governor falls aud releases the pawl. Of course this is a great saving in the matter of wear and tear and expenditure of gas. The advantages possessed by the gas engines when compared with steam may be summed up in the stat ement that the cost of running them for gas is 3d per hour per horse power. The one in use at Messrs Suckling’s has been engaged for eleven working days eight hours per day, driving all the machinery on the premises, and the cost of gas for that period has been 7s 6d. The larger one in Mr Turner’s store has carried on all the heavy foisting work required iu a largo grain store for twenty-live working days at a cost of 255. The engines can be started at a moment’s notice, and at once give out their full power, and no gas is burnt whilst the engine is standing still. F arther than this, insurances are not disturbed by the use of these engines. The large hoisting engine in Mr Turner’s store is fitted to lift weights up to 30cwt. It is fitted with an 18in. diameter barrel and gearing including reversing gear. One rope lowers whilst the other lifts, and the gearing is controlled by two hand ropes, so that in case of accident the _ whole may at once be stopped. The adaptability of these engines to hoisting and their economy has been fully tried with the one spoken of, and it is intended to have another placed there shortly. The first cost is not large, and no doubt when their efficiency and small cost for running becomes more widely known, a large number will come into use in our manufactories and merch nts’ warehouses.