244

MODERN STEAM PRACTICE.

suit almost all attendants when arranged for the right hand. Thelever for the brake is worked by foot; it should be of great length,and so placed that the attendant can press it with his left footwhilst he holds the reversing handle. The brake lever must, ofcourse, be arranged horizontally, and fitted with a cross shaft andshort lever at the end for taking the brake strap of wrought ironlined with blocks of wood. The shaft is supported on three pillowblocks, and is fitted with a weighted lever, the weight being suffi-cient to balance the long foot lever, which should have a suitablestop to keep it always at a convenient height for treading upon.Many engineers are of opinion that it would be better to fit a handlever and rod to the long brake arm, instead of pressing on it withthe foot; but it must be borne in mind that both hands may berequired at times to lift or depress the link motion, and the footcan be applied to the brake when the engine requires to be sud-denly stopped. In other examples the long brake handle is placedabove the floor of the engine room, the engineman moving it byhand, and the handle is kept up by a catch cast on a suitable cast-iron column: there is another catch placed on a nut worked by ascrewed rod and wheel, supported by the column. The nut can beadjusted at pleasure to suit the wear of the wooden friction blocks.When the handle is depressed and Sprung under the catch theblocks are pressed against the friction wheel, and when the frictionrequires to be increased the wheel on the screw rod is turned byhand, which firmly locks the friction blocks.

The piston for all horizontal engines should be of the strongestand lightest construction possible, fitted with a single packing ring,and the usual junk ring. The packing ring may have Steel springsbetween it and the body of the piston; but some makers prefer aplaited gasket. The junk ring is bolted to the piston with screwedbolts and nuts recessed in the body of the piston. Another formof piston largely used for high-pressure engines is a plain casting,turned on the rubbing surface, and recessed for light steel springs.This is certainly the simplest form of metallic packed piston; andwhen it is supported by means of the piston rod passing throughstufhng boxes at each end of the cylinder, it works admirably evenfor large diameters. The method of connecting the piston to therod is by forming a coned part at the middle of the rod with acorresponding cone turned in the piston, which is secured by acotter passing through the body of the piston, as in the ordinary