The momentum acquired
from the magnet by the short arms, A and S, is sufficient to move
the long arm up to the position of L'. To lock the door, press the
button and the momentum acquired from the magnet by the short
arms, now at A' and S', is sufficient to move the long arm down
from L' to the position at L.
--Contributed by Benjamin Kubelsky, Chicago.
** Direct-Connected Reverse for Small Motors [60]
A simple reverse for small motors can be attached directly to the
motor as shown in Fig. 1. Fig. 2 shows the construction of the
reverse block: A is a strip of walnut 5/8 in. square and 3/8 in.
thick with strips of brass or copper (BB) attached as shown. Holes
(CC) are drilled for the wire connections and they must be flush
with the surface of the block. A hole for a 1/2 in. screw is bored
in the block. In Fig. 1, D is a thin strip of walnut or other
dense, hard wood fitted to the binding posts of the brush holders,
to receive the screw in the center.
Before putting the reverse block on the motor, remove all the
connections between the lower binding posts and the brush holders
and connect both ends of the field coil to the lower posts.
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