Note: Remove power from unit before mak
ing adjustments.
1.04
When the requirement calls for the clutch
to be disengaged, the clutch shoe lever
must be fully latched between its trip lever and
latchlever so that the clutch shoes release their
tension on the clutch drum. When engaged, the
clutch shoe lever is unlatched and the clutch
shoes are wedged firmly against the clutch drum.
When the main shaft is rotated by hand, . tbe
clutch does not fully disengage upon reaching its
stop position. In order to relieve the drag on
the clutch and permit the main shaft to rotate
freely, apply pressure on a lug of the clutch
disc with a screwdriver to cause it to engage
its latchlever and thus disengage the internal
expansion clutch shoes from the clutch drum.
Note 1: After a few weeks (300 to 500 hours)
j
of operation of a new unit, the unit should
be
relubricated to make sure all operating points
have been properly lubricated.
2: Recheck all clutch gaps to insure that
the parts, after seating
th
emselves, have not
caused the clutch gaps to open upo Reset if
necessary. Standard readjustment periods
are to be maintained thereafter.
1.05
The covers may be removed for inspec-
tion and minor repair of the unit; how
ever, when more extensive maintenance is to be
undertaken, it is recommended that the unit be
disconnected from its source of power as a
safety precaution.
1.06
References made to left, right, up, down,
front, or rear, apply to the set in its op
erating position, as viewed from the operator's
position.
1.07
All electrical contact points should meet
squarely. Contacts with the same dia
meter should not be out of alignment more than
25 percent of the contact diameter. Check con
tacts for pitting and corrosion and clean or bur
nish them before making specified adjustment or
tolerance measurement. Avoid sharp kinks or
bends in the contact springs.
CAUTION: KEEP ALL ELECTRICAL CON
TACTS FREE OF OIL AND GREASE.
1.08
Units may have signal contacts made of
either unplated or gold-plated tungsten.
If
in doubt as to the type of contacts, remove
contact box cover and inspect contacts for gold
ISS 5, SECTION 573-127-703
plating. Do not use burnishers, files, etc which
will remove gold plating.
1.09
Use twill jean cloth (KS2423) (TP107162)
to clean gold-plated contacts. Open con
tacts. Allow contacts to close on surface of
twill jean. Draw twill jean part way through.
Open contacts and withdraw twill jean.
1.10
This procedure prevents small fibers at
edges of twill jean strip from becoming
lodged between contacts.
1.11
Clean unplated tungsten contacts in ac
cordance with s t a n d a r d procedures
(Paragraph 1.07).
Servicing For Certain Low-Voltage Applications
1.12
For standard applications, including those
with data sets, observe standard main
tenance procedures and intervals. Certain low
voltage applications are covered below.
1.13
For optimum reliable operation in these
low-voltage applications, c l e a n gold
plated contacts with twill jean, as instructed
above, at intervals of approximately 50 hours of
actual contact operation. Since maintenance in
terval and life expectancy of the contacts are
dependent on the signal circuit, maintenance
interval may be lengthened for specific applica
tiohs.
Note 1: Applying operating voltage of stand
ard Distortion Test Set directly to contacts
may damage gold plating and impair low
voltage operation. When electrically adjust
ing or testing contacts (2. 22), use an inter
mediate device, keyed by the contacts, to
interrupt current to stroboscopic lamp of
test set. This intermediate device must be
capable of being keyed by a 3 to 20 volt
change at maximum of 20 milliamperes.
Note
Normally for low-voltage applica
tions, contacts should be used in circuits
operating between 3 and 20 volts de at a cur
rent .level not to exceed 60 milliamperes.
Between 20 and 70 volts de the current should
be adjusted so as not to exceed a 120 milli
watt power level. The contacts are not nor
mally intended for use with voltages above 70
volts de. Exceeding this level for an appre
ciable length of time may result in damage to
the gold plating and make them unfit for low
voltage applications.
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