04.29.08
A complete K
A complete K.B. lock-out telephone is shown in Fig. 190. This is the
type of instrument that is usually furnished when new equipment is
ordered. If, however, it is desired to use the K.B. system in
connection with telephones of the ordinary bridging type that are
already in service, the lock-out and selective mechanism, which is
shown on the upper inner face of the door in Fig. 190, is furnished
separately in a box that may be mounted close to the regular telephone
and connected thereto by suitable wires, as shown in Fig. 191. It is
seen that this instrument employs a local battery for talking and also
a magneto generator for calling the central office.
The central-office equipment consists of a dial connected with an
impulse wheel, together with suitable keys by which the various
circuits may be manipulated. This dial and its associated mechanism
may be mounted in the regular switchboard cabinet, or it may be
furnished in a separate box and mounted alongside of the cabinet in
either of the positions shown at _1_ or _2_ of Fig. 192.
In order to send the proper number of impulses to the line to call a
given party, the operator places her finger in the hole in the dial
that bears the number corresponding to the station wanted and rotates
the dial until the finger is brought into engagement with the fixed
stop shown at the bottom of the dial in Fig. 192. The dial is then
allowed to return by the action of a spring to its normal position,
and in doing so it operates a switch within the box to make and break
the battery circuit the proper number of times.
_Operation._ A complete description of the operation may now be had in
connection with Fig. 193, which is similar to Fig. 189, but contains
the details of the calling arrangement at the central office and also
of the talking circuits at the various subscribers stations.
[Illustration: Fig. 191. K.B. Lock-Out Station]