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 CHAPTER VI MACHINE SHOPS—AXLES AND WHEELS Axles. Straight axles are turned to gauges in special axle lathes. Formerly these lathes were of the ordinary form with a headstock at the left-hand end and a poppet head or tailstock at the right. The most modern form of lathe is of the centre-driven type, in which the axle after having been turned in the middle is gripped and driven there, supporting tail-stocks being used at each end. This method gives a more rigid support for the axle, and enables cutting tools to be used at both ends. Fig. 24 shows a lathe of this type, which admits axles 9 ft. long. A straight axle is illustrated in Fig. 23, in which A A are the “wheel seats,” i.e., the portions on to which the wheel centres are pressed, and B B are the “journals” which revolve in the bearings in the axle-boxes. The collars C C keep the journals from moving laterally. The wheel seats and journals are turned smooth and truly circular and the journals are finished with