Akf Mechanism - GE AK-2-50 Maintenance Manual

. 3. Remove the closing spring assembly by
removing· .the upper and lower spring pins (1, 31).
-
.
.
4. Remove the right ·hand bearing · side plate
(20), and the side plate shims (18)
if
present,. by
removing four mounting bolts (19), thus allowing
the main closing crank (25) to be removed.
5. Remove the closing handle (22)byremoving
two set screws threaded in same hole.
6. Remove the front escutcheon by removing
four screws holding it to the front frame center
support.
7. Remove the handle return spring (29) by
unhooldng either end of the spring.
8. Disconnect the top end of each pawl spring
(7).
9. Remove ·the roll ~in (24), thus allowing
the closing handle shaft. (23) and pawl assembly
(2~) to be.re.moved~
JO.
Remove the ratchet wheel (17) and its
assembly (16) by removing Nylok* screw (15)
and thrust bearing (12).
If
shims (13) are present
they must also be removed.
11. Remove front bearing plate (9) by removing
three mounting bolts (10) accessible from thefront
of the breaker. The mechanism is now completely
disassembled. It is not recommended that any
of the subassemblies removed during the above
operation be further disassembled in the field.
Replacement sub-assemblies should be obtained
from the factory.
12. To reassemble the mechanism, reverse
_the procedure described above. :
NOTE: When reassembling tpe mechanism the
adjustments listed below should be checked at
. the appropriate . time of ·reassembly. The
appropriate time for each adjustment is in-
dicated in the adjustment text. ·
Adjustments
(Fig. 15). ·
Frequent adjustments to the mechanism sh~uld
not be required. If · the mechanism has been
disassembled, it will be necessary to check the
following adjustments: ·
1.
It
may be necessary to . add shims (13)
to reduce the end play . of the ratchet wheel shaft
(16). ·
An
end play of 0.010 to 0.020 of an inch
is recommended. Shims should be obtained from
the factory.
2. It may be· necessary to add buffer stop
shims (27) to the buffer stop (26) to provide a
clearance of 1/64 to 1/32 inch between the pawls
(21) and the buffer stop, when the pawls are
touching the ratchet wheel teeth extending a max-
*
Tra_ d e-mark of Republic Steel Corp.
Low Voltage Power Circuit Breakers GEK-7303
imum distance from the center of rotation of
.. the ratchet wheel (17). This measurement should
be made while operating the closing handle during
the four spring charging operations and before
the closing springs are reassembled~
3. The -ratchet pawls (21) should operate
freely throughout the closing strokes. .They
should engage the ratchet wheel teeth. near 'the
end of each counterclockwise and clockwise stroke
of the closing handle with a definite clicking sound,
indicating a free non-binding operation. After
the clicldng sound is detected, the closing handle
should have a minimum overtravel of 1/2 in. or
3 1/2 degrees, measured at the end of each handle
stroke • ..
4. · The groove pin ·· (14) in the front of the
ratchet wheel assembly (16) must be assembled
in a manner that Will allow Nylok screw (15)
to be tightened securely. A clearance· of 1/64
to 1/32 in. should exist between the front of the
groove pin and the rear surface of the Nylok
screw head.
Other adjustments . to the closing and operating
mechanisms, such
as·
complete contact and latch
adjustments, may be made by following the pre-
vious. l y d~scribed instructions for the AK-50, -75
and -100 breaker mechanisms.
FIELD DISCHARGE
CONTACTS.
FIELD
WINDING
FIELD
SWITCH
DISCHARGE •
RESISTOR .
)
Fig. 16 (4_ 15A845)· Typi~al connection diagram
AKF· MECHANISM
(Fig.
17f .
The Type AKF breakers are two-pole breakers
with field discharge contacts placed in the center
pole. When this br~aker is ·opened, the field
discharge contacts close, thus connecting an ex-
ternal discharge resistor across the field of the
generator or motor. When the breaker is closed,
the field discharge contacts are opened. See
Fig. 16 for a typical circuit connection.
19