300

DETAILS OP SCREW ENGINES.

the rod passes through both details, as illus-trated by Fig. 158.

the extremity of the cranked shaft, and thus thesetting of the valve is effected without stopping

Fig. 157.

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The arrangement of the gearing is simplyaccomplished as follows. On the extremity of

Fig. 158.

MESSES. MAUDSLAV’S REVOLVING EXPANSION GEAR.

the engines. The small crank in front of theFig. 159.

MESSES. RAVENHILL’S EXPANSION VALVE AND CASING.

the crank shaft is secured a mitre wheel; acounter shaft—with a wheel at each end—im-parts motion to a bevel wheel on the valvespindle. A plan and elevation of the gearingis depicted by Fig. 159. The alteration ofthe grade of expansion is effected by a groovedbarrel, situated directly behind the mitre wheelon the counter shaft. A hand wheel is usedto turn the shaft, and a lock nut retains therequired position for the valve. This arrange-ment will be more readily understood byalluding to the sectional view of the same—shown in the elevation. The mitre gearingis disconnected by the clutch and coupling on

MESSES. RAVENHILL’S EXPANSION GEAE.

coupling is for the purpose of working thehand pump when required.

It will be remembered that in all the pr e *