The door is drawn open to show the amount of bulge it should be hammered to. In the center a hole should be drilled through which to pass the screw used to close it, which is attached to the loose bar, A. The handle, B, is then screwed up tight.
The door is circular and must be large enough to overlap the opening about half an inch and have a couple of bright iron or brass eyes, C, riveted on to form the hinge.
Next comes the back-pressure valve, Fig 36. A is a front view with plate by which it is bolted to the boiler, as at W, Fig. 20.
It is very simple to make, and consists of the casting A with top and bottom covers and the ball-valve B, which ought to be ground with a little emery and oil to fit perfectly. It acts in this manner.
The water being forced up C from the pump, raises B and passes into the boiler. On the up stroke of pump, the pressure is removed from under B and the pressure of steam in the boiler causes it to fall back and close the opening entirely, preventing any water from passing away from the boiler. A small flange can be put on each outer side of the boiler near the furnace to support it on bed-plate level with smoke box.
The boiler should now be covered with flannel, cut to shape and wrapped round the body part and a casing of sheet tin put over it and secured by brass bands and small nuts underneath--as shown in Fig. 20.
The steam supply pipe can now be connected with the cylinders and it should be made forked as in Fig. 37. A leads from steam pipe and branches off to each cylinder, where it must be screwed up with white lead.
The exhaust pipes B B should be of larger tubing and bent round up the sides of the smoke box so as to be out of the way when you have to clean the tubes. A small brass pipe, C, must also be passed through the chimney, bent upwards and fitted with a tap which should take the steam from the top of the boiler and be used as shown at D F Fig. 20. This helps to raise steam very quickly.
Fig. 38 is a rear view of the foot plate and shows the necessary fittings which you must either make or buy to complete the model.
The cocks you might make but the water gauge you must buy. A is the furnace door, B two gauge taps, C starting-lever handle, D spring balance safety valve, F wind-guard with two look-out holes, G steam whistle handle, H pressure gauge, N the quadrant and lever for reversing the engine, O the rear buffer beam with buffers, P the wheels showing axle, R R the springs for same and V the safety-guard rail on either side.