Allis-Chalmers MA-150, Instruction Book

Page: 16 / 48

As
the charging 1 nkage
c
h
a
r
g
e
s the ma!n closing springs the motor
switch cam rotates with the left hand large gear (4-3). Just
before the springs are fully charged the cam (2) throws the 88-3
sw1tch and when the springs are fully charged the 88-J and 88-2
switches are thrown by lever
(I)
which is operated by pin (5) .
To adjust these switches loosen lock nuts (4) and turn adjusting
screws
{3) in or out w! th
a
screwdr l ver, Proper operation sequence
is as fo
I
I ows,
When the control is energized the motor starts to charge the springs.
The 88-lbb switch opens when the springs are fully charged, however,
before this sw!tch opens the 88-3aa switch closes connecting the
resistor Into the motor circuit. The motor continues to drive the
gears unt!J the free sw1nging cranks (4-4) on the main gears are
almost to the top of the gears. The motor then shuts off (cut by
the cam operating the 88-3aa switch), and allows the cranks to go
over center, and drop out of the way.
The resistor is adjusted to limit the speed of the unloaded motor.
It Is factory set to operate the motor at rated and minimum voltage
a
nd
I
imit the coast of the motor so that the pin on the gear coasts
past top center but not beyond 10 o•cJock. With too much resistance
the motor will stall. With too
I
ittle resistance the motor wi
II
coast too far and the cam wil
I
reclose the 88-3aa switch and the
motor will continue to run
3.14 RESET RELAY (For instantaneous Reclosure Service Only)
The ALLiS-CHALMERS Reset Relay designed for use in circuit breaker
control is a rugged electronic solid state time delay which operates
a small relay" The relay contacts are rated at 15 amperes,
The relay closing time fs not affected by broad variance of voltage
and current well beyond the standard circuit breaker control limits.
The time delay error caused by temperature is minor being less than
3% from -2ooc to +80°C and not over 5% to -40°C
The voltage regulator and timing circuits are mounted on a printed
circu�t board and encapsulated In a resilient material for shock
resistance"
The controlled supply voltage charges the capacitor (CJ) through
the time rate determining resistor RJ to the triggering voltage of
the unijunction transistor
(UJT)
which activates the SCR energizing
the relay col
I"
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