Another Rung Up the Producer-gas Ladder
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Means for Overcoming a Fundamental Difficulty. Novel Application of Blower Solves Time-lag Problem and Dispenses with Need for Petrol AN inherent characteristic of the producer-gas vehicle is time-lag between throttle opening and power development. Bar that remaining in the system when the throttle is closed, no gas to speak of is induced by the engine until the fire has been drawn up sufficiently for new gas to be generated. The length of the lag depends largely upon the period for which the throttle has been closed or nearly closed_ The phenomenon is most marked after descending a long hill, or standing for some while with the engine ticking over slowly.
Clearly, a method of completely surmounting the difficulty, which can, of course, be minimized by employing highly reactive fuel, is to maintain a draught through the producer the whole time. This is the basic object of a device incorporated in a plant recently installed on a Bedford Luton-type van by Arlington Motors, Ltd., Ponders End, Enfield. This vehicle is equipped with Bellay apparatus, and the whole may be regarded as a joint and admirable effort of the above-named company and Cm Producers (Benny), Ltd., 66, Victoria Street, London, S.W.1.
As for the efficiency of its functioning, we can write from personal
experience, having travelled a considerable distance in the vehicle and having been most favourably impressed by the manner in which the aim has been achieved. In point of fact, it seems that more than this has been accomplished and that some slight supercharging effect, or at least an improved volumetric efficiency, has been attained. Moreover, the vehicle is rendered wholly independent of petrol.
There is much ingenuity in the mechanism employed. Included in the gas system between the mixing valve and the manifold is a blower, drawing from the producer and discharging either to the engine or to an escape pipe. It is driven, when the engine is running above a predetermined speed, by a belt from the crankshaft through a free wheel. When the engine is stationary or running slowly, it is driven by an electric motor.
To control the last named, there is, in addition to the master switch, an
automatic mercury switch. This is mounted on the throttle operating linkage in such a manner that the circuit is broken by the first quarter of an inch of pedal movement. Simultaneously, the escape valve is closed and further movement only opens the main throttle.
Thus, every time the throttle is closed the escape valve is opened and a draught maintained through the fire, the suction being effected by the engine, so long as it is running fast enough, and by the electric motor if the revs, fall too low. For lighting up the fire, the master switch is closed and
the throttle kept shut until a supply of gas is available.
To operate the escape valve and mercury switch, a link is mounted, roughly vertically, between the end of the throttle arm and the escape-valve rod. To a point nearer the former than the latter the pedal rod is attached. For the first motion, the link swings with its lower point of attachment as fulcrum, and operates, with mechanical magnification, the escape valve, tipping over the mercury switch at ,the same time. For subsequent motion the upper end of the link becomes the fulcrum and the throttle is operated.
This clever device is typical of what the good brains in our industry are doing—of the valuable assistance our transport engineers are giving to the national effort.