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the guard or splash disc. This latter portionis to prevent the condensed steam from scald-ing the attendants, and scattering itself in theengine room. The means of adjusting thespring is by a telescopic cross piece, above thespring, and the set handle retains the requiredposition for both. The handle at the extremityof the valve spindle is to prevent the valvefrom turning during the adjustment of thespring.
The constant means of adjusting the springis not always essential, as the example,Fig. 12 9, by Messrs. Bavenhill, indicates. This
Fig. 129.
messes, eavenhill’s cylinder belief valye.
is an ordinary valve and springs enclosed ina casing, and the securing of the latter alonecompresses the spring. The advantages withthe casing are, that the spray, when the valveis opened, is transmitted direct into thebilge; and the spindle and spring beingenclosed within the casing, are thus guardedfrom fractures by the fall of any weightybody.
Independently of the valves under notice,relief plug valves are often attached to thecylinders, their use being that, in the event ofblowing through, or extreme priming fromthe boilers, a simultaneous discharge can beeffected. Messrs. Humphrys introduce anaddition to these valves beyond the plug, whichis an india-rubber flap valve, the closing ofwhich excludes the air from the cylinder;thus the vacuum is unaffected while the plugvalve is opened.
Some consideration to this matter has beenbestowed by ourselves, and the result is theproduction of the next two examples of relief
Fig. 130.
BIJEGH 8 CYLINDER BELIEF VALVE.
valves. The illustration, Fig. 13 0, is an eleva-tion of a triple disc valve, which embraces allthe advantages of the spring and plug valves,while dispensing with the latter. The positionsof two of the valves, as shown, are as requiredwhen blowing through. On the return strokeof the piston, the upper or return vave willfall on the india-rubber seatings. and thus the