As the cylinders may be taken as the best examples of setting cores and securing their vents, the foot or drag plate may be taken as an example of an irregular joint, and the setting and wedging of chaplets. It consists of a heavy casting, having projections for securing the brake cylinder and the brake shaft carriers. It is shown in longitudinal section in Fig. 66, and transverse section in two planes in Fig. 67, Fig. 68 with its scale being an isometric view of the core M, which is the principal one in this casting, the minor cores being the lightening ones M'. The top halves of each are necessary as making-up pieces, because the prints of these lightening cores and the body core M are nearly at the bottom of the pattern, which has to be drawn, and N, Figs. 66 and 67, is secured by the bolts b for the clearance, for bolting the easting to the frames. It is bottom poured at P, the tail end of the casting, the leaders having a break and connecting runners for convenience, winch also lessens the fall of the metal, the facing strip P' being formed by a loose strip on the pattern, and there is a riser at R, Fig. 66.

Fig. 62.

Scale 1 1/2" = 1 Foot.

Fig. 63.

Fig. 64.

Scale 1" = 1 foot.

Fig. 65.

Scale 1" = 1 Foot space.

In the first instance the pattern is fixed face downwards and packed up, the bottom box placed in position and rammed, cinders being put in layers opposite the holes in the box for venting. After the first casting has been made, the top joint is used as a turnover board for the pattern, which acts as a kind of print and indicates at once the exact position the pattern should occupy, without any further measurement or setting. After the bottom box has been rammed up it is turned over, and if the top box has been used as indicated, the old sand is knocked out, the box placed in position, the pattern lined up with facing sand, gaggered about every 4-inch space, rammed with backing sand, and vented all over.

Fig. 66. Section G.H.

Reference has already been made in the general remarks to the making of irregular-parted joints. As a rule, an angle of about 60° to 80° will give a satisfactory lift, as at K, Fig. 66. K' would give an easy free lift, but necessitates using a great number of gaggers, whereas K" would only be made use of by a most inexperienced moulder, and such a man would use a riddle full of sprigs in making this joint. The core M does not require bottom chaplets, because the core iron is of sufficient strength to carry it from print to print, such a core iron being capable of carrying a core of 6-feet span between prints. This core is vented by the gases striking through the cinders, and conveyed by the vent pipe through the aide of the box. Another method, and the one most frequently adopted in venting this core, is to bring the cinders up to the joint to meet those in the box, and then the joint is securely made, so that the metal cannot burst in on the cinders. The core for the drag pin is placed in position, and the joint passing through the large core M secured.

In the section. Fig. 66, only two chaplets are shown, but five are used; three along the centre, and one each side, at the broad end. They must be so wedged down that the pressure of the metal due to head cannot force the core up and destroy the formation of the casting. Their heads must be made to rest fair and square upon the core, the moulder clearly satisfying himself by trial that this is the case, and as little blocking (which should be avoided) and wedging as possible. All this is absolutely necessary, because frequently castings are lost through inattention to chaplets. In the case before us, it is the custom to place a 5-ton weight upon the top box for weighting purposes, and it is so fixed that there shall not be more than about ¾ inch space between the bottom of the weight and the top of the chaplet stem. It is then possible to fairly secure them with two small wooden wedges. There should be a small clearance of sand round the chaplet stems, otherwise in pushing them down upon the core, or the vibration set up in wedging, may cause sand to fall out and damage the contour of the casting, the metal forming small fins round the steins. In some cases buttons are formed in the top joint, so that if the metal blows round the stems, it can be chipped away in dressing to form a good surface. When bottom chaplets are necessary, equal care must be bestowed upon setting them, especially if wood blocks are used. The blocks must be bard, so that the chaplets will not settle with the weight of the core or the wedging of the top chaplets. Such large moulds as the foot or drag plate are only skin dried, and cast while hot, which is necessary to prevent moisture striking through the skin again. This gives a good surface, and at the same time the backing sand, not having been baked hard, is very porous, and allows the gases to permeate with great freedom.

Fig. 61. Section C D D E F A B.

Fig. 68.

Fig. 69 is a longitudinal section of the combined sand box and splasher, Fig. 70 a transverse section through two planes of the sand-box, and Fig. 71 a simple section through the splasher, 5/16 inch metal throughout, except at the foot and stud holes. Six core-boxes arc required, viz.: sand-box, inlet and outlet for the sand, bridge for spanning over the inlet core, foot of the sand-box and splasher core. The sand-box core is vented by means of the pipe, the gases passing up the channel scooped out of the sand, Figs. 69 and 70, and the splasher core by means of the vent wire, the gases striking through the print, Fig. 71. Studs and chaplets are carefully set and wedged in the position shown, and the casting is run by means of three gates 2 inches by « inch at K, Figs. 69 and 70, upon the top of the front edge of the sand-box, not seen in the views given, but the position of which is indicated by the dotted lines, a riser coming off at R, Fig. 69.

Fig. 69. Section E F.