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PLATE XXIV.
REDUCING-VALVE FOR OBRY GEAR.
Air enters at the nipple, a, on the end of the valve casing, passes into the axial channel of the valve, b, through the radial holes, c, and emerges into the pressure-chamber, d, through the axial hole in the screw, e.
The diaphragm, f, is of thin German silver, and is held on the seat, gg, by the cover, h, and to the valve by the screw, e.
The pressure in the chamber, d, causes the diaphragm, f, to yield, owing to its pliability, and as it buckles downward it forces the valve, b, downward until it is fully seated upon the valve-face, k. Supply air is thus cut off until the pressure in the chamber, d, is sufficiently reduced by
the Obry steering engine through the nipple, l, when the valve again opens admitting air.
A hole at, m, permits the free escape of air that may leak by the valve into the chamber, n.
If necessary a paper washer may be laid on the seat, gg, tinder the diaphragm, f. Increasing the thickness of this washer makes the valve more difficult to seat, and hence gives greater average working pressure. The valves are adjusted in manufacture to work at 150 300 lbs.
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