7.1 2.2 F AND G SWITCH ADJUSTMENT
For proper electrical operation, the F and G mechani
cally operated switches must operate at the proper point in
the closing cycle. If these switches are to be replaced,
measure the distance between the tip of the switch button
and the bracket on which they are mounted. When the new
switch is mounted, duplicate the measured dimension ,
then check for proper operation.
When a normal closing o peration occurs, the ratchet
usual ly comes to a stop with an arbitrarily designated
ratchet tooth No. 1 , Fig. 37 , engaged by the holding pawl.
This tooth is the one which is in line with an i m ag inary
line passing through the centers of the camshaft and the
rivet o pposite the roller on the ratchet assembly. It is a
matter of no concern if the action stops on a d ifferent
tooth, but it is i mportant to positively identify tooth No. 1
by the method described.
To check the switch action, after tooth No. 1 has been
identified, turn the camshaft with the maintenance handle
and count the teeth as they pass the holding pawl. By using
a continuity tester, observe when the switches operate as
the ratchet turns. The normally open F switch on the left will
close, and the G switch will open.
Electrical breakers should operate the switches while
moving from tooth No. 10 to tooth No. 1 1 .
If this check shows that an adjustment is needed, the
switch to be corrected can be moved closer to or farther
away from the paddle which operates the switches. A very
thin open-end 5/8-inch wrench will be needed to loosen or
tighten the nuts which fasten the switches to the bracket.
7.1 3 DRAWOUT MECHANISM
The drawout mechanism shown in Fig. 38 moves the
breaker through the DISCONNECTED, TEST, and CON
N ECTED positions. Fig. 39 shows how the drawout
mechanism is mounted to the breaker.
As the racking handle is turned, the internally threaded
trunnion moves on the screw threads, rotating the hex
shaft, on the ends of which are fastened the arms which
engage the fixed pins in the drawout enclosure.
The trunnion travels between the two jamb nuts on the
end of the screw, and the adjustment sleeve, which stops
the trunnion movement at the other extreme point of its
travel . The trunnion is against the jamb nuts when the
breaker is fully racked out and against the sleeve when
fully racked in.
The racking mechanism is adjusted at the factory as
sembly operation so that the action is stopped in either
direction at the precisely correct point. The jamb nuts are
set so that when the tru nnion is against them the relation
between the arms and the equipment pins they engage is
shown in Fig . 38. The length of the sleeve, which is free to
slide on the threaded shaft, is controlled by the amount of
thread engagement between the sleeve and its collar. This
length is adjusted to stop the trunnion when the distance
between the ends of the equipment and breaker studs is
.032" to .21 8" . After this adjustment is made, the sleeve
and its collar are locked together by the set screw.
1 TOOTH
FIG. 37 - LOCATION O F RATCH ET TOOTH
N0. 1
.
29
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