. Locomotive engineering : a practical journal of railway motive power and rolling stock . 24-inch engine, havingports l^ by 17J4 inches, as only 112pounds without packing strips. He quotes extensively from those whouse the valve and who advocate it for anybut low speeds. Among those quoted areE. M. Herr, Joseph Cockfield and VonBorries. It is claimed that as more ; admitted than with the plain valve theengine is more powerful, and one case iscited where a 16 by 24-inch engine withAllen valve: did as satisfactory work onfreight as a 17 by 24, as long as the speedwas fair. At very low
. Locomotive engineering : a practical journal of railway motive power and rolling stock . 24-inch engine, havingports l^ by 17J4 inches, as only 112pounds without packing strips. He quotes extensively from those whouse the valve and who advocate it for anybut low speeds. Among those quoted areE. M. Herr, Joseph Cockfield and VonBorries. It is claimed that as more ; admitted than with the plain valve theengine is more powerful, and one case iscited where a 16 by 24-inch engine withAllen valve: did as satisfactory work onfreight as a 17 by 24, as long as the speedwas fair. At very low speed the lattercould outpull the former. The wavy compression line which al-ways accompanies the Allen valve, attributes to the high-pressuresteam which is confined in the Allen portbeing admitted to the compression side ofthe piston as the valve moves over toadmit steam at that end of the increase of pressure causes a few im-pulses on the indicator piston and pro-duces the wavy compression by which anAllen valve can nearly always be dis-tinguished by its 244 LOCOMOTIVE ENGINEERING June. 1899. Case-Hardening and Annealing. BY FRED H. COLVIN. One of the first shop mysteries whichthe apprentice runs up against is the case-hardening of small pieces by the toolmaker or blacksmith, and in the averageshop it remains something of a mystery, asthere is very little of it done. The methodemployed is usually the simple one of dip-ping the pieces into prussiate of potashafter heating to a cherry red, heating againif it has cooled any in the dipping process,as small pieces are apt to, and finallyplunging in water. This leaves a hardsurface to a very slight depth—perhaps asixty-fourth of an inch—and is not apt tocolor to any extent. The more ambitious way of the smallshop is to take a piece of gas pipe of goodsize, screw a cap on one end, and makeone for the other having a few small holes from three to six hours. Larger pieces re-quire much longer, all nigh
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroa, bookyear1892
