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A REPAIRER'S CONTRIBUTION T( ROAD TRANSPORT EFFICIENCY

3rd August 1940, Page 30
3rd August 1940
Page 30
Page 31
Page 30, 3rd August 1940 — A REPAIRER'S CONTRIBUTION T( ROAD TRANSPORT EFFICIENCY
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WHILST the Sheepbridge Stokes Centrifugal Castings Co., Ltd., Chesterfield, is widely known, it is by no means so generally realized that there is an associated company, Sheepbridge Stokes Engine Liners, Ltd., in London. The works of this concern are at 26, Raymouth Road, Bermondsey, S.E.16, and its activities, as in the case of the northern company, centre upon cylinder lining.

This, as the name implies, is the main specialized service it offers, but, besides this, and in addition to kindred processes, such as reseati-ng valves, sleeving brake drums, etc., general automobile engineering (particularly of a heavy nature) is undertaken. Engines and other components are overhauled. Even complete commercial vehicles will be accepted, but the practice of submitting for treatment anything other than just the part or unit affected is discouraged for a variety of excellent reasons.

When the removal from a chassis of a component for repair and its subsequent replacement are undertaken, the object is only to assist the customer, who might not be al:4e to carry out such incidental work himself.

Adjoining the Sheepbridge Stokes premises are the works of Skelton, Sleat and Co., Ltd. The function of this company is general engineering, and the two establishments operate in close alliance and are definitely complementary to one another.

Whilst the former is equipped primarily for its specialized work, the latter incorporates a drawing office, a jig and tool-making department, a forge and an excellent machine shop, included in which, for example, is a facing lathe capable of taking jobs up to 4 ft. in diameter. Some idea of the size of these two concerns may be formed from the fact that the combined personnel numbers about 150.

• Big Stock of Sleeves and Inserts •

In the stores of the company with which we are now directly concerned we observed a big stock of liners of a wide variety of sizes and types, together with a comprehensive range of valve seat inserts. Both are supplied by the Chesterfield parent company, the standard liner, or sleeve. being of Centricast Loded iron.

If hardened liners he specified, Centrard sleeves, nitrided to over 900 Brinell are employed. In the main, the sleeves kept in stock are finish-ground externally, the bore being slightly undersize for final machining after insertion. Some unmachined sleeves are also kept available for turning to non-standard sizes.

The valve-seat inserts are distinguished by the trade mark Centrilock. Their outer surfaces are machined to two

diameters, differing by 0.010 in. To receive them the cylinder block or head is similarly bored and the inserts are pressed in, larger end first, so that, once home, they are immovable. Stellite-faced seats can also be inserted in this manner.

Accompanying pictures show some of the operations involved in sleeving a cylinder block: In the ease of a unit that has not formerly had liners, the casting is first bored out. For this job, Town vertical borers are used. For inserting the sleeves, a powerful hydraulic press is employed, and it is of note that this is hand operated, a feature which enables the operative to exercise far better control when inserting a sleeve than would be possible with a power press.

Final boring is performed on Thompson fine-boring machines, and the ultimate finish is produced by honing, for which operation Kitchen and Wade machines are employed.

Blind cylinders, of course, cannot be honed, but must be ground, and we were surprised to observe in the shops several specimens of castings of this type. They represent. perhaps, a sign of the, times—an indication of the efforts that are being made just now to keep old vehicles on the road and running.economically. When hardened liners are used they are ground after insertion. For this operation there is a pair of Churchill universal grinders. On this type of machine the small grinding wheel rotates rapidly on its own axis and slowly revolves about the axis of the cylinder bore.

A similar eccentric action characterizes a special too! employed for grinding valve seats after insertion. In this case the main axis is located by the valve guide and the grinding wheel follows a perfectly concentric path around it.

• Machine Tools for Precision Work • Among other outstanding items of equipment in these works may be named Churchill crankshaft grinders, a surface grinder of the same make and a number of lathes, including large tools capable of dealing with brake drums the lining of which is another speciality of Sheepbridge Stokes Engine Liners, Ltd., centrifugally cast sleeves being used, as for cylinders.

There are also another powerful press for straightening axles, etc., an Anunco big-end borer, a main-bearing borer, and degreasing apparatus. The Ammco tool is of the type that cuts from both ends—one rough, the other fine, perfect parallelism between the big and little-end bores being ensured by the job holder. In this connection it is interesting to observe also the methods employed for preserving alignment, in the other operations. The crankcase lower face is always the working basis. From it the main bearings are bbred, the block top is faced and the cylinder bores are finished.

For remetalling bearings there is a separate bay, equipped for the execution of work of a comprehensive nature, whilst' the fitting shop forms a separate department. Here there is adequate but limited space for vehicles under repair. It is equipped throughout with a compressed-air system. We observed in it also a plant for water-testing cylinder castings, the jackets being normally subjected to a pressure of 40 lb. per sq. in.

To sum up, our visit to these works made it patentlk clear to us that nothing was spared to maintain in London the reputation associated with Chesterfield. From the foregoing description our readers will be able to judge for them selves the quality of the equipment installer]. It is necessary for us to add only $hat the atmosphere pervading the Bermondsey establishment is one of such efficiency and good co-operation between worker and executive that the standard of workmanship can hardly fail to reach at least the same level.

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