Warner Electric PCBC-1525_1225 - Manual (Page 15)

15 Warner Electric • 800-825-9050 P-214 • 819-0518
Heat: Excessive heat and high operating tempera-
tures are causes of rapid wear. Units, therefore,
should be ventilated as efficiently as possible,
especially if the application requires fast, repetitive
cycle operation.
Foreign Materials: If units are used on machinery
where fine, abrasive dust, chips or grit are dispelled
into the atmosphere, shielding of the brake may be
necessary if maximum life is to be obtained.
Where units are used near gear boxes or transmis-
sions requiring frequent lubrication, means should
be provided to protect the friction surfaces from oil
and grease to prevent serious loss of torque.
Oil and grease accidentally reaching the friction
surfaces may be removed by wiping with a rag
dampened with a suitable cleaner, which leaves no
residue. In performing this operation, do not
drench the friction material.
If the friction materials have been saturated with oil
or grease, no amount of cleaning will be completely
effective. Once such a unit has been placed back
in service, heat will cause the oil to boil to the sur-
face, resulting in further torque loss.
Torque Loss: If a brake or clutch slips or loses
torque completely, the initial check should be the
input voltage to the magnet as follows:
90-Volt Series: Connect a DC voltmeter with a
range of 0-100 or more directly across the magnet
terminals. With the power on and the potentiome-
ter turned up, a normal reading is 90 volts,
although 85 to 95 is satisfactory. The reading
should drop as the potentiometer control is adjust-
ed counterclockwise.
24-Volt Series: Use a DC voltmeter with a range
of 0-30 volts or more. A normal reading is approxi-
mately 22-26 volts.
6-Volt Series: Use a DC voltmeter of approximate-
ly 0-15 volt range. A normal reading is from 5.5 to
6.5 volts.
The above checks normally are sufficient. Further
checks may be made as follows: a low range
ammeter, when connected in series with one mag-
net lead, will normally indicate approximately .40
amperes for the 90 volt units, 1.0 ampere for the
24 volt, and 3.5 amperes for the 6 volt series.
These readings are with the power on and the
potentiometer control in the maximum position.
Ohmmeter checks should be made with the power
off and the circuit open (to be certain, disconnect
one lead to the magnet). Average resistance for the
90 volt series is 220 ohms; for the 24 volt, 20
ohms; and for the 6 volt series, 1.5 ohms. A very
high or infinite resistance reading would indicate an
open coil.
If the above checks indicate that the proper volt-
age and current is being supplied to the magnet,
mechanical parts should be checked to assure that
they are in good operating condition and properly
installed.