P.O. ENGINEERING DEPT.
Issue 2, 8.10.53
ELECTRICAL CLOCKS - PULSE TYPE
Clock No. 46 - Description
The Clock No. 46 is an electrically-driven master clock with a half second beating pendulum, and is used to control
chargeable time clocks in telephone exchanges.
It provides the following pulses:-
- 1 second.
- 6 second.
- Three 1 second pulses during each 6 second period.
The carriage U is linked to the pendulum by the forked detail L, and swings in unison with the pendulum. Carriage U carries all the controlling toggles and
pawls, whose functions are as follows:-
Toggle T1 trails over the notched agate G1 and as the arc of the pendulum swing decreases, the toggle momentarily engages in the agate notch, causing contacts
C1 to make and complete the circuit for the pendulum drive-magnet
M. A non-inductive resistance S is connected across contacts C1 to reduce sparking.
Toggle T2 rides in the notched agate G2 and operates the 1 second spring-set C2 each time the pendulum swings to the left. C2 is normally adjusted to make for
150 ms., but this period can be altered by moving the agate to left or right.
Pawl B rotates the count-wheel A one tooth for each complete swing of the pendulum. Every sixth tooth is deeply cut and allows pawl B to operate the
6 second spring set C3, by engaging the trip pawl D.
3. The three 1 second pulses every 6 seconds are derived from the normal
1 second pulses by the operation of spring-set F which is controlled by a cam-wheel situated behind wheel A. This spring-set
makes for 3 seconds in every 6 seconds.
The pendulum is regulated by raising or lowering the pendulum bob P by means of the rating nut. Raising the bob causes the clock to gain.
Manufactured by Gents, Magneta Time Co. or Gillett and Johnson.
The Gents clock can be identified by two screws fixing the count mounting
Diagram - GMT33.
Drawings - 44, 45 and 63158.
Drawings - CD 474, CD260 and P/T 46.
These clocks occasionally gave rise to radio interference.
Click here for EI Radio
Early model (Picture dated 1933)