VALVE SEATS
Page 61
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Details of a Successful Method by Which They Can be Renewed.
THERE are various ways in which worn valve seats in cylinders can be brought into condition for further use, the chief being building up the seats by welding, or turning out parts of the cylinders and fitting collars on 'which the new seats are machined.
The latter process is the one particularly developed by the Andrews Crankshaft and Cylinder Co., 312-314. Brad ford Street, 'Birmingham.
linless the greatest care be exercised in fitting, there is, in the ordinary way, a possibility of such collars becoming loose; either 'under the effects of vibration or of unequal expansion and contraction between the mass of the cylinder and the collars; but any risk of this is entirely obviated in the interesting .process used by this company.
Our drawing shc .Ing a collar partially inserted into a bored recess in the cylinder will serve to illustrate how this is attained. Each collar has a 'cast-iron ring upon which the new seat is cut. The actual material employed is centrifugally east and has a Brinell reading of 200, so that it really stands up to valve hammer much better than ordinary cylinder •iron, which is inserted 'comparatively soft, so that these inserted seatings need grinding much less than what may be termed the original seats.
Each collaris slightly coned at its base so that the lower periphery forms what is practically a knife edge. At the base of'the boring which receives the collar there is a coned undercut of slight depth; and the collar, being forced into • pesition under very, high pressure, the coned periphery meets the bottom of the boring and is forced outwards into the undercut,. thus forming. an effective dovetail.
The cost is stated by the company to be no more than in
the case of a collar inserted in the usual manner. Many thousands of these seats have now been fitted without a single failure, whilst the expense, as against some other processes, is fractional.
Certain licences for the operation of this patent system have already been granted, whilst the works of the company are in a position to fit these seats in a day. It is claimed that some users of transport vehicles are saving hnndreds of pounds per year by employing this patented system.