. American engineer and railroad journal . in. realstretih), and the point of the cord opposite the lower cud ofthe stretched banc! is marked ; the cord is now detached fromthe engine, and the last point marked is tied to the lower endof the rubber band, and the cord again secured to the engine just as at first. The apparatus is now ready for use ; thedetent is thrown in and the engine started. At each revolu-tion the rubber band takes up all the slack and keeps a mod-erate tension on the cord, and whenever a card is taken orremoved, and the detent thrown out or in, the action of theband takes
. American engineer and railroad journal . in. realstretih), and the point of the cord opposite the lower cud ofthe stretched banc! is marked ; the cord is now detached fromthe engine, and the last point marked is tied to the lower endof the rubber band, and the cord again secured to the engine just as at first. The apparatus is now ready for use ; thedetent is thrown in and the engine started. At each revolu-tion the rubber band takes up all the slack and keeps a mod-erate tension on the cord, and whenever a card is taken orremoved, and the detent thrown out or in, the action of theband takes up all sudden shock, and yet is too light to haveany effect on the tension of the cord when the detent is outand the barrel spring working. In the illustration the detentis shown in gear and the throw of the indicator motion at itsleast distance from the indicator. On locomotives a canvas dust-cover can be used over theindicator, and the apparatus kept in place during a long runwithout injury, so that a most valuable set of cards may be. A DEVICE OP VALUE TO INDICATOR-CARD TAKERS. secured marking the different powers on heavy and lightgrades and at various speeds. For dynamo engines we know of nothing so well suited asis this appliance, and the cost of running these engines maybe clearly shown by fair card. Roughly taken cards serve nopurpose here, the points of cut-off and the lines of expansionbeing too indefinite to indicate leaky pistons, a source of lossmore frequent in this kind of machinery than any other, andone which counts heavily in the coal bill. A. A. W. THE ACCURACY OF VALVE-GEARS. To the Editor of Tiik AMERICAN Engineer : It is a common remark of inventors and their friends in de-scribing the claims of new valve-gears to say that they aremathematically correct, or that they give an excellent ornearly perfect distribution of steam. Mr. David Joy madesuch a claim in first describing his radial valve gear (see Pro-ceedings of the Institute of Mechanical Engineers,
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
