OP-755 Part 2 Pages 197-401 - Personal Page of GENE SLOVER

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(b) Undervoltage protection.- A contactor dropout
arrangement, which functions at potentials
of 110 volts or less, provides the undervol tage
protection.
r c ) Overload protec tion is of the inverse time
limi t thermal type with magnetic reset mechanism.
Two of these devices are connected in
separate phases of the motor circ~it. At occurrence
of overload of sufficient duration
the head from each unit is transmitted to a
fusible alloy tripping device which causes the
main line contactor to open. Thereafter depressing
the "start" button of the push-button
station causes the resetting mechanism to reposition
the overload contacts. Whenthe con-
.taets have reset, the main line contactor closes
and in closing de-energize's the coil of the
resetting mechanism. \o1i th normal setting of
60 amperes and with load at 72 H.P., 100 amperes,
the device will trip in less than one minute.
The adjustment range is 59.1 to 71 amperes.
9. A-end. - The A-end oonsists of the main operating
pump, safety relief valves, case with oil reservoir, control
valve block, timing and control mechanisms and a motor starting
interlock switch and earn. This subassembly is shown on
drawing 271679. The electric motor shaft end (opposite the
auxiliary pump end) is direct coupled to the operating pump
drive shaft. The coupling is described in paragraph 11. All
other elements of the A-end are of the type, arrangement and
functional purpose indicated in the sUbparagraphs below. (Nomenclature
underlined.)
(a) The operating pump is a multiple piston variable
stroke type. It rotates at motor speed
but delivers pressure fluid to the B-end,
through connecting leads, according to the direction
and degree of tilt or offset. Such
offset is imparted from the hand control lever
through the control linkage and the pump yoke.
(b) The pump yoke is the mechanical element through
which pump reciprocation is varied from lion
center" (neutral) to full stroke. Whenthe
yoke is on center the pump is idling and is
not displacing fluid. (At neutral the pump
delivery is also by-passed by the valve arrangements.)
Shifting the yoke off center
gives pump displacement through the closed
system to the B-end. Shifting in the opposi t.e