rotation of the ratchet wheel (17) This measurement
5-13. Breaker Disassembly , Assembly and
should be made while operating the e closing handle
during the four spring charging operations and before the
closing springs are reassembled
If it is necessary to replace any of the
(3) The ratchet pawls (21) should operate freely
mechanism parts the following total procedure is
throughout the closing strokes. They should engage the
used. This procedure may be halted at the step
ratchet wheel teeth near the end of each counter
required to replace any particular part.
clockwise and clockwise stroke of the e closing handle
with a definite c licking sound indicating a free non-
binding operation. After the c licking Sound is detected,
(1) Install the safety pin as described in paragraph 5-
the c closing trundle should have a minimum over travel
of 1/2 inch or .3 1/2 degrees measured at the end of each
(2) Separate the front and rear frames as described
(4) The groove pin (14) in the front of the ratchet
(3) Remove the closing spring assembly by removing
wheel assembly (16) must be assembled in a manner that
the upper and lower spring pin ( 1, 31, fig. 5-1).
will allow Nylock screws (15) to be tightened securely A
(4) Remove the right hand bearing side plate (20)
clearance of 1 / 64 to 1/ 32 inch should exist between the
and the side plate shims (18) if present, allowing the main
front of the groove pin and the rear surface of the Nylock
closing crank (25) to be removed.
(5) Remove the closing handle (22 ) by removing two
5-14. Overcurrent trip EC-1 Replacement AK 2-50
set screws threaded in same hole.
a. Remove breaker from compartment
(6) Remove the front escutcheon by removing four
b. Separate front and rear frames per paragraph
screws holding it to the front frame center support.
c. Remove the bolts holding the c oil to the lower stud.
(7) Remove the handle return spring (29) by
d. Before installing a new device, check the travel of
unhooking either end of the spring.
the trip arm with a rod and wire and push the armature
(8) Disconnect the top end of each pawl Spring
solidly against the magnet. The trip arm should travel at
(9) Remove the roll pin (24) thus allowing the closing
least 5/ 32 inch.
trundle shaft and pawl assembly (23) to be removed m.
e. Replace new device in reverse order of steps a, b,
(10) Remove the ratchet wheel (17) and its assembly
c, and d.
(16) by removing Nylock screw (15) and thrust bearing
(12). If Shims (13) are present they must also be
f. Adjust device as described in TM 5-6120-250-12.
5-15. Power Sensor Trop AK 3-50 5 Breaker
(11) Remove front bearing plate (9) by removing
a. General The AK-.3 type power sensor trip functions
three mounting bolts ( 10) accessible from the front of the
with solid state components with the exception of the
solenoid trip which is used to trip the breaker on a signal
from the power sensor unit.
The power sensor
overcurrent trip device consists of four major
(1) To reassemble reverse the order described in
components: 1-the magnetic coils around the breaker
conductors 2-the power supply which provides both the
(2) It will be necessary to check the adjustments give
tripping energy and the comparison basis for overcurrent
in subparagraph c.
detection, 3- the power sensor unit with the various pickup
c. Adjustments When reassembling the mechanism the
settings and time delay selection taps and 4-the trip
adjustments listed should be checked at the appropriate
solenoid which physically trips the breaker.
time during reassembly. 'The appropriate time for each
b. Tripping. The breaker is tripped open by the
displacement of a mechanism latch. This allows a toggle
(1 ) It may be necessary to add shims /13, fig. 5-1)to
linkage supporting the movable contacts in the closed
reduce the end play of the ratchet wheel shaft (16) An
position to collapse. This trip latch is fastened rigidly to a
end play of 0.010 to 0.020 of an inch is recommended
trip shaft which runs horizontally from left to right through
(2) It may be necessary to add buffer stop shims (27)
the breaker. All the means provided for tripping the
to the pawl buffer stop (26) to provide a clearance of 1/64
breaker operate through striker arms.
to 1 / 32 inch between the ratchet pawls (21 ) and the
buffer stop. when the pawls Is are touching the ratchet
wheel teeth extending a maximum distance from the