The Pusher Control Device.—Before the motor is installed in the hull the pusher control device which opens the compressed air valve must be made and mounted on top of it.
On top of the motor, as you will see by looking at [Fig. 16], there is a metal name plate, which is fastened to the top of the field magnets by four screws; unscrew the latter and take off the plate.
Now make a pillow block, as the bearing for the threaded spindle is called. Saw out with a hack saw[12] a base plate of sheet brass ⅛ inch thick, 1 inch wide, and 1½ inches long; drill four ⅛-inch holes in the corners of the plate, so that it can be screwed down to the field magnets of the motor.
Also drill two ⅛-inch holes lengthwise in the middle of the plate and have the first one ⅛ inch from one end and the other ½ inch from the same end and in a line with the first hole.
Take a brass bar ¼ inch thick, ½ inch wide, and 1⅝ inches high, and drill two 3/32 inch holes in one end of it, to correspond to the two holes in the middle of the base plate, and thread these to fit a couple of 6-32 machine screws.
Next drill a ⅛-inch hole clear through the top of the bar, or standard, as it is now called, 3/16 inch from the top. This must be very accurately done, in fact, it ought to be done with a drill press, for if it is not precisely at right angles to the base, the spindle will not run true, and besides there will be a great loss of power.
Drill a hole through the top of the standard until it meets the hole through which the spindle is to pass, and by means of this top hole keep the spindle well oiled. The pillow block is shown complete in [Fig. 15] and [17].
To make the spindle, get a piece of soft steel rod ⅛ inch in diameter and 4½ inches long. Thread it from one end to within 1⅜ inches of the other end, and screw on a nut as far as it will go. Push the smooth end through the hole in the pillow block; slip a collar over the end close up to the standard, and screw it fast. To make the pusher mechanism complete put a grooved pulley 1½ inches in diameter on the end of the spindle up close to the collar and screw it fast.[13]
