Axleboxes. The account of the work done in the wheel shop may conveniently include the axleboxes. These are most frequently machined in the general machine shop, but as they have to be fitted to the journals they are, in some modern works, machined in the wheel shop, where they are close to the wheels, and do not then require to be taken from one shop to another. An alternative method, used in other works, is to fit and bed the axleboxes on to a short “dummy” axle journal, kept in the machine shop for this purpose, the axleboxes then being taken straight to the erecting shop.
Axleboxes are either of gun-metal or of cast steel fitted with gun-metal bearings, the latter form being now more usual. The “brasses” which bear on the journals are provided with recesses, into which is run “white” or antifriction metal, consisting of about 80 per cent. of tin, 10 per cent. of copper, and 10 per cent. of antimony.[1] This prevents the journal of the axle from being injured in case the bearing runs hot.
The boxes are arranged on a planing machine, in two rows of about ten boxes in each row, and planed between the jaws to receive the brasses and axlebox keeps, which are machined in turn and fitted into the boxes. The brasses must be fitted very carefully, and they must be well bedded down to avoid any rocking action of the
- ↑ The composition of “white metals” varies considerably. The above figures give one mixture used for locomotive bearings. Many white metals contain from 40 to 70 per cent. of lead, which replaces the tin.
