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Rh condemned, the wheels forced off by hydraulic pressure, and a new axle substituted. Other than flaws, the chief running defect is oval wear of the journals which work inside the axleboxes, and a similar oval wear of the crank pins of driving axles. To restore the journals to a true circular form the wheels are put into a wheel lathe, and a very light cut is taken off the axle journals. For truing up crank pins of crank axles, a portable machine is clamped to the crank webs. The axle remains stationary, and the cutting tool revolves round the crank pin.

Axleboxes. These wear on the flanged sides which are constantly moving up and down in the hornblock guides under the action of the springs. The thrust and pull of the rods on driving and coupled axles accentuate this wear on the axleboxes of such axles. As the hornblock guides also wear, the latter are faced up first. This may be done in place on the engine either by filing them up, using a surface plate to detect the high places, or by means of a portable facing machine, or the horn blocks may be removed and re-ground. The axleboxes are then “lined up,” i.e. the deficient width across the faces of the hornblocks is made up by riveting a brass liner on one side or by white metalling this side to the proper thickness. The side is then planed and the box fitted into the hornblocks. The crown of the brass which bears on the journals will be worn down and the box will generally require a new brass; if not too