LOCOMOTIVE ENGINES.
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cranks; but in many examples of inside-cylinder engines the axleshave no outside bearings, but simply a broad bearing with the side ofthe brasses rubbing quite close against the flat sides of the crank.This plan has been very generally adopted both for broad and narrowgauge engines; it is certainly much simpler than the cranked axlehaving outside bearings on the main framing and likewise narrowbearings fitted to the horn plates; moreover the breadth over allis greatly reduced, the outside coupling rods being placed quiteclose up to the wheels. In manufacturing cranked axles a longslab is hammered up, and then swaged down in the middle and atthe ends; the throws are then worked into shape, and the axle isthen twisted at the central part, until the throws are at right angleswith each other—the grain of the iron running across the throws;by this method they are not so liable to split through. Somecranked axles are bent with the aid of hydraulic machinery, a longbar being heated and put into the machine; the throws are formedwith a die and mould, the die being pressed up by water power:these axles give great satisfaction.at the factory the throws are gen-erally solid with the ordinarymethod of construction; they arethen slotted out, and the axle isthen turned in a lathe. All thecorners of the bearings should bewell rounded, as the axle is greatlystrengthened thereby. In somethe crank pin is turned of thesame diameter throughout withbold curves at the corners, while inothers the pin curves from themiddle to the sides of the crank; by this means greater strength isobtained over those that are finished parallel. The ends of the crankthrows are rounded at the outside corners, thereby reducing theweight, while others are left quite square, the extra weight beingbalanced on the wheels. In some examples a wrought-iron strap hasbeen shrunk on each crank, with the view of binding the fibre of theiron better together; this we consider may be to acertain extent advis-able, although it adds more weight, which must be properly balanced;on the other hand, when due attention is paid to the selection of thescrap iron, with good workmanship, and with the improvements
When the axles are delivered
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