Silencing Foden Slide Valves.
Page 20
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THE slide valves on Foden wagons are held to their respective seatings entirely by the pressure of the steam, which is admitted into tile chest through the inlet port situated above eacih valve.
Owing to wear a slide valve may develop an objectionable rattle, which is noticeable when the engine is running single or light. This is caused 'by the valve falling away from its seating and rubbing against the cover of the steam chest.
The fault can easily be remedied. There are various ways, but that advised by the makers is the following:— The cover is removed and, if care be taken, the gasket can be used again. An engineer's rule is then placed across the chest and another rule, graduated in 1-64 in., utilized to measure the distance between the first straight-edge and the back of the slide valve.
After this measurement has been taken it is necessary to measure the projection of the lugs on the steam chest cover. Again place the straiThtedge across the lugs on the cover and measure the distance between D and E, as shown in our diagram. This distance must correspond with thp c36 clearance gap to which we have already alluded, and to make it do so it will probably be necessary to take a cut, bv the aid of a shaper, right round the steam chest cover.
An allowance for the jointing must, of course, bQ made, and the correct clearance for the valve is 1-64 inso that when the cover is tightened up the valve should slide easily ithout rattle.