# Steam Locomotive Construction and Maintenance/Chapter V

CHAPTER V
MACHINE SHOPS—FRAMES AND CYLINDERS
Fig. 17.—Frame Plate.
and all are slotted together at one operation, the top frame only having been marked off, and the proper outline drawn upon it. The next operation is to mark off and drill all the bolt and rivet holes, of which there will be from 300 to 400 according to the size and type of engine. The holes for bolts and cold rivets are drilled ¹⁄₁₆ in. less than the finished diameter, so that they can be reamered or “rose-bitted” out by the erectors when fitting up the cylinders, stays, and brackets to them. About four or five frames are drilled together in one batch, of which the top one is ​marked off, and this plate is afterwards used as a template or drilling “jig” when the later batches are drilled. In some railway works separate frame templates or jigs are used for standard classes of engines. These consist of plates about ¾ in. thick in which all the holes are drilled in their exact positions but larger than the holes in the frame. The holes in the template or “jig” are then bushed with steel bushes, the internal diameters of which are the exact diameters of the holes as drilled in the frame. This jig is placed on the top of the frames to be drilled, and the bushes act as guides for the drills. The drilling is done in multiple radial drilling machines, which may be either special machines or of the radial type shown in Fig. 3.
The drilling completed, the frames are placed upside down in a vertical position in screw jacks or trestles provided with arrangements for holding them in this position. All sharp edges are then removed and the corners of the recesses into which the hornblocks fit are rounded. The frames are again laid on their sides, the hornblocks are bedded down and fitted into the recesses slotted in the frames to receive them, and the various brackets are also bedded down to their proper places. The bolts which secure the hornblocks are turned to exact size, and must be driven in to be an absolutely tight fit. The main frames are then sent to the erecting shop, a pair being required for each engine. The bogie requires an additional pair of small frames. These together ​with the buffer beams of steel, cross-stays, etc., are dealt with in the frame shop in a similar manner to the frames themselves. The riveting together of the cross-stays and frames is always done in the erecting shop, only the plates themselves being treated in the frame shop.
Fig. 19.—Marking-Off Cylinders.
Fig. 20.—Marking-Off Cylinder Port Faces.
Fig. 21.—Double Boring Machine for Cylinders. By Craven Bros., Ltd. (Manchester).
Fig. 22—Cylinder Boring and Drilling Machine. By Messrs. William Asquith, Ltd. (Halifax).
The planing of the various sides and flanges, and also of the steam chests port facings, when the latter have ordinary slide valves, may be done either on an ordinary large planing machine or on special machines made for the purpose. The cylinders have to be set on the machine by the bore to plane the top and bottom surfaces.
In those works in which the boring is done before the planing, one method is to use two standards which are splined underneath, the tongue or spline fitting into one of the grooves in the table of the planing machine. The top part of each standard is provided with a circular face plate which just fits into the counterbore of the bored cylinder. The standards are placed so that the face plates enter the counterbore at each end, and they are pulled up to grip the cylinders by means of a long central bar with nuts. The centre line of the bore is thus held ​perfectly parallel to the bed of the table so that all surfaces parallel to this can be planed accurately.
A large number of holes have to be drilled in the flanges for the cylinder and steam chest covers, and for uniting the cylinders to the frames. Fig. 22 illustrates a modern machine by Messrs. William Asquith, Halifax, for doing this work. It is also used for facing the front flanges to which the cylinder and steam chest covers are secured.
All joints are carefully faced, and covers fitted on to be perfectly steam-tight. The cylinders should then be tested, preferably by steam pressure, though hydraulic pressure is sometimes used.