Warner Electric PCBC-825, PCBC-1000, PCBC-1225 - Manual (Page 14)

14 Warner Electric • 800-234-3369 P- 205-01
•
819-0474
Burnishing and Maintenance
Burnishing
Intimate metal to metal contact is essential
between the armature and the metal rings (poles)
of the magnet or rotor. Warner Electric clutches
and brakes leave the factory with the friction
material slightly undercut to assure good initial
contact.
Normally, the desired wearing-in process occurs
naturally as the surfaces slip upon engagement.
The time for wear-in, which is necessary to obtain
the ultimate torque of the unit, will vary depending
on speed, load, or cycle duty.
If maximum torque is required immediately after
installation, the unit should be burnished by
slipping the friction surfaces together at reduced
voltage. It is recommended that the burnishings
be done right on the application, if at all possible.
Burnishing at high speed will result in a smoother
wear-in pattern and reduce the time for burnishing.
The voltage should be set at approximately 30%
or 40% of the rated value.
The unit should be cycled on and off to allow
sufficient time between slip cycles to prevent
overheating.
When a Warner Electric brake or clutch is
properly assembled and installed, no further
servicing, lubrication, or maintenance should be
required throughout the life of the unit.
Maintenance
Wear Pattern: Wear grooves appear on the
armature and magnet surfaces. This is a normal
wear condition, and does not impair functioning of
the unit. Normally, the magnet and armature, as a
mating pair, will wear at the same rate. It is the
usual recommendation that both components be
replaced at the same time.
Remachining the face of a worn armature is not
recommended. If a replacement armature is to be
used with a used magnet, it is necessary to
remachine the worn magnet face. In refacing a
magnet: (1) machine only enough material to
clean up the complete face of the magnet; (2)
hold the face within .005" of parallel with the
mounting plate; and (3) undercut the molded
facing material .002" - .004" below the metal
poles.
Coil Data
Unit Size PB & PC-825 PB & PC-1000 PB & PC-1225
Voltage — DC 6 24 90 6 24 90 6 24 90
Resistance @ 20°C — Ohms 1.27 20.4 223.3 1.23 19.7 248.7 1.33 22.2 61.7
Current — Amperes 4.74 1.18 .4 4.87 1.22 .36 4.5 1.08 .34
Watts 28 28 36 29 29 33 27 26 31
Coil Build-up — Milliseconds 170 170 170 205 220 235 300 320 350
Coil Decay — Milliseconds 70 75 80 70 75 80 190 190 190
Notes: Build-up time equals current to approximately* 90% of steady state value and flux to 90%.
Decay time equals current to approximately* 10% of steady state value and flux to 10%.
*Approximately because current leads or lags flux by a small amount.