. Science of railways . he working parts need bedisturbed to examine the valves and repair same whennecessary. These jacks will work horizontally to two-thirds oftheir run-out limit. The rocker shaft which oper-ates the pump rod passes througha stuffing-box to prevent leakage,and terminates in a square boss. This permits of the lever beingapphed in any one of four po-sitions, which is frequently ofgreat advantage when workingin cramped quarters, clearingaway wrecks, etc. fill the jack,remove slotted screw in the head. The best fluid for tilling ismade one part water, six partsa
. Science of railways . he working parts need bedisturbed to examine the valves and repair same whennecessary. These jacks will work horizontally to two-thirds oftheir run-out limit. The rocker shaft which oper-ates the pump rod passes througha stuffing-box to prevent leakage,and terminates in a square boss. This permits of the lever beingapphed in any one of four po-sitions, which is frequently ofgreat advantage when workingin cramped quarters, clearingaway wrecks, etc. fill the jack,remove slotted screw in the head. The best fluid for tilling ismade one part water, six partsalcohol and one-half part of goodoil (sperm preferred), well shaken together beforeputting in the jack. Never use coal oil, wood alcoholnor water only in filling, as the two former destroy thepacking, and the latter may burst the cylinder infreezing weather and rusts the metal. In using the jack, press the lever with a quicksurge, and move the handle upwards suddenly, inorder to give the valves a chance to react Fig. Hydraulic Jack. LOCOMOTIVE APPLIANCES. 663 The thumbscrew valve should be screwed outwardsa few turns when raising a load. In lowering, screwthis valve inwards slowly. This valve, being inde-pendent of the pumping mechanism, gives absolutecontrol over the speed or distance of the loweringweight, and a half turn of the thumbscrew will stopthe load at any point without the slightest jar. Should the jack refuse to work on account of thevalves sticking to their seats or from air entering thepump, by striking the lever a few sharp blows, up anddown, the valves will be jarred loose and the airexpelled.
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