The New Beardmore Fuel Pump
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MHE Beardmore oil engines displayed
at the Glasgow Motor Show this week incorporate the latest fuelinjection pump (Patent No. 376,388), of which we are able to give a full account. William Beardmore and Co.,. Ltd., Parkhead, Glasgow, has for some time been perfecting the design with the object of producing a pump of which the cylinders and plungers would not be subject to known caukes of severe
The hardened plungers are cam-operated and of constant stroke. Variation in the rinantity of fuel injected is obtained by partial rotation of the plungers, but the helix is not cut in the plunger top, as in the old type of pump in which it engaged with a port in the cylinder liner. Instead, the plunger has an axial hole connecting with two transverse holes (diametrically opposite, but at different levels), and the fuel is fed to the top of the plunger through these ports from a shaped annular cavity in the cylinder liner.
On the bp stroke injection commences when the upper plunger port passes the 'upper edge of the surrounding cavity, the lower port then being well below the lower edge of the cavity. Injection continues until the lower port commences to pass the lower edge of the cavity, at which moment escape takes place: It is necessary only to add that the lower edge of the annular cavity is helical to show how, by turning the plunger, the commencement of escape can be advanced or retarded, so decreasing or increasing the quantity of fuel injected.
The advantage of the design is that the plunger is not subjected to side thrust at the top upon a sharp-edged helical crown, which would tend to cause ridging of the liner. The plunger extends some distance above the transverse ports, giving lateral support both above and below the points where the fuel streams are cut. It is balanced so far as side loading is concerned.
It is possible to chamfer the plunger crown in order still further to reduce any fear of wear upon the liners ; all sharp edges are removed from the periphery.
Timing is controlled by a sliding camshaft collar, with straight and helical splines.
The liner, which, of course, is fixed. is made in two parts, the upper part being recessed and fitted over the lower part to form the reception ports and the annular cavity with straight upper and helical lower edge.