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OIL ECONOMISING BY PISTON.

14th February 1918
Page 14
Page 14, 14th February 1918 — OIL ECONOMISING BY PISTON.
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The Split Skirt Acts as an Oil Scraper Ring and Gives Other Advantages.

The patented piston which is being produced in large quantities by the Aerolite Piston Co., Ltd., of Hanover Court Yard, Hanover Street, London, W. 1, has for its aim the more perfect fit of the skirt of the piston to the cylinder, secured in the simplest possible Way. Whilst the Aerolite piston is of usual design, it is turned to a slight taper at the skirt so that, at that point, it will

just nbt completely enter the cylinder. Longitudinal slots or sa.wents are then made in this taper portion, 64 that, when the piston is pushed into the bore of the cylinder, the natural spring of the metal will Make the bottom of the skirt a close fit in the bore.

The split skirt acts, first of •all, as a scraper ring which on the downward journey removes from the cylinder walls all excess oil, which is an advantage in manufacturing considerations and to the user. The quantity of oil that is needed to be splashed by the big ends on to the cylinder walls calls for a considerable amount of skill in designing and care in manufacture, but, obviously, if the pis

ton can be made efficiently to do the work.,ei removing all excess there will be no need to do more than make a rough adjustment of the oil supply in the ease of a trough fed system, or a rough adjustment of the oil pressure in the case of pressure feed. Thus more liberal lubrication for the big ends and gudgeon pins may he' allowed for, whilst, the oil being prevented from passing up above the piston, there is a minimum of car bon deposit on the piston head and on the valves and valve Se-stings. When the engine is Wing need as a brake, or is being driven on a nearly closed throttle, oil is not sucked up into the combustion chamber.

The pisten does not necessarily remove all oil from the bore, as the skits permit a certain quantity to remain, and this amount can be varied by increasing or reducing the number of holes or slots in the piston skirt according to the results of experience.

A second function of the split. skirt is to reduce in a most remarkahle_manner the slap of a piston. Being a perfect fit in the •bore, this slap may be said

to be entirely eliminated, which allows the benefit to be obtained from a. full advance of the ignition. A point that will appeal to users is that a notable redustion in oil consumption is secured by the use of these pistons. In the ease of one car tested, the oil consumption was reduced from one pint per 150 miles to one pint per 800 miles. Tn another ease the results were even setter, the previous consump tion having been one pint per 100 miles and with the new piston only one pint per 983 miles; thus nearly ten times the work was obtained from the oil supply.

These pistons are :made in cast-iron, steel or aerolite alloy., the pistons made of the latter material having already earned a name for high quality, excellent manufacture and good results. One test Made with an engine fitted with aerolite alloy pistons made in the manner desCribed, proved that the car could be run up a steep hill until the engine stepped without any slap whatever. The same engine with ordinary pistons and the same advance knocked freely long before stopping.

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Organisations: US Federal Reserve
Locations: London

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