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kept very low, with the bed extended well under the cylinder, which is supported by means of a foot at the extreme end of it. The exhaust valve is placed in the main cylinder casting on the centre line, and the air, gas, and timing valves in the short back cover.
This firm have recently constructed an engine having a single cylinder 24 inches diameter, with a stroke of 30 inches, intended to run at 150 revolutions per minute, which it is said will develop 196 1.H.P. when using producer gas; and in order to mitigate the difficulties experienced in lifting the exhaust valve against the terminal pressure, which in this engine would be about one ton upon the head of the valve, they have arranged an auxiliary valve which, whilst actuated by the same lever, is lifted in advance of the main one.
TANGYES' GAS ENGINE
With such dimensions and forces inherent in these large engines, the difficulties are not in the construction of an engine to withstand the heavy pressures so much as in overcoming the results of these forces when aggravated by the differential stresses resulting from the high temperature of combustion and unequal effect of the cooling water in the jacket.
In these large engines, when working at full load and using high compression, the combustion chamber is liable to become so hot that early firing ensues, the incoming charge being fired before end of compression stroke.
The above engine, like all Messrs. Tangye’s large sizes, is fitted with their hand-pressure starter.
J. E. H. Andrew & Co. (Limited), Reddish This firm commenced making gas engines as far back as 1878, in which year the late Mr. Andrew acquired the rights of the Bisschop engine at the Paris Exhibition, and continued manufacturing that type only until 1883, when they brought out the first Stockport engine, designed to give an impulse every revolution when working at full power, of which type they manufactured some thousands, and forming, before the expiry of the
Otto' patents, the most formidable rival Messrs. Crossley had; but, like all the other engines, the Stockport, as then known, disappeared when those rights expired. Fig. 31 is a part sectional elevation, fig. 32 a sectional end elevation, and fig. 33 a perspective elevation of a 21 B.H.P. engine. The distinguishing features of this firm's designs are, that up to 85 B.H.P. the bed and cylinder are cast in one, and the back cover or combustion chamber attached to it by bolts, which go through its whole length. The air valve box is bolted to the end of the combustion chamber and is water-jacketed, the air inlet pipe passage forming part of the cylinder casting, opening into and fitted with baffle plates in the base. The exhaust valve box is bolted to the side of the combustion chamber, not in the direct line of explosion, and is also water-jacketed. No gas cock is fitted other than that on the gas bag on most of the sizes. The method of providing against the effects of frost is by making the metal forming the extreme end very thin, so that this point should be the first to give when the water expands in freezing.
In their 54 B.H.P. engine (shown in fig. 34) the centre line is kept very low and the bed extended well under the