Fitting Centrifugally Cast Cylinder Liners.
Page 28
If you've noticed an error in this article please click here to report it so we can fix it.
CONSIDERABLE progress is being V./made in the employment of new liners for cylinders instead of grinding out the bores and fitting oversize pistons. We have already dealt with this matter editorially in a general manner, besides referring to several concerns which have adopted the system. It may, however, be of interest to refer to the activities of a company which is doing a large amount of work in this connection and which, in addition, is using its own centrifugally cast iron for the liners.
The company in question is the Sheepbridge Stokes Centrifugal Castings Co., Ltd., Sheephridge Works, Chesterfield, the work in London, however, being carried out by an associated company, Sheepbridge Stokes Engine Liners, Ltd., 26-28, Raymouth Road, London, S.E.16.
In each case the cylinders are bored out .1J in. larger all round than when
new—in other words, in. on the diameter—and a liner of this thickness is forced in by means of a hydraulic press. The outside of each liner is ground a few thousandths of an inch larger than the cylinder, and this effectually prevents any movement after fitting, but to secure the liner still further a small flange or lip is provided at one end, and this fits into a recess machined at one end of the cylinder ; if the head be detachable, the flange comes at the top of the cylinder and is then held by the head, but where the head is integral with the block, as often happens with old-pattern cylinders, the liner is driven in from the lower end, the flange then being held by the crankcase.
A feature of the process is that the liner is ground to the correct size after being forced into position.
The use of a particular grade of cast iron for these liners exercises a great effect upon the wearing quality and strength. It is claimed that engines equipped with these liners wear twice as long as the ordinary cylinder bores, and figures in support of this , have been supplied by a bus-operating company, the results being obtained after the treatment of over 1,000 engines. It is well understood that bus work throws excessive strains upon an engine,. so that this should afford really satisfactory proof.
Besides dealing at these works with cylinders worn oversize in the ordinary course of running, liners can be fitted in the case of engines in which one bore only has been badly scored or cracked, such a repair being carried out at only a fraction of the cost of grinding the bores and fitting oversize pistons throughout.