A Laminated Piston Ring
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Cords Ring Designed to Accommodate Itself to Uneven Wear in Cylinder Bores
ATYPE of piston ring which would appear to incorporate features of an unusual nature is that known as the Cords, a product of Cords Piston Ring Co., Ltd., 30, Hampstead Road, London, NAVA. It is laminated in construction, being comprised of a number of segments in fine-grained alloy metal.
Apart from its properties of sealing a normal bore, it is also claimed to provide an effective seal in worn bores, by reason of the manner in which the laminations accommodate themselves to irregularities. It will be appreciated, too, that the cup formation of the assembly is responsible for lateral pressure in the ring groove.
Another feature for which claims are made, and one which strikes us as B42
being of some importance, is that improvement in bore lubrication should result frodi the action of the oilretaining channels which exist between the segments. In consequence of the segments being staggered, there is no end gap, or source of direct leakage, past the ring.
It is usual to arrange for each piston to carry two Cords rings, the uppermost ring being of the normal compression type. In cases of bore wear up to 1.0 thousandths of an inch, standardsize Cords rings are fitted, but in cases of wear exceeding this figure, oversize rings are used.
In sizes from 76 mm. to 101 mm. the price per ring is 3s. 6d., extra being charged when the width of the ring groove calls for more segments.