Rexnord Stearns AAB 320 Series Quick guide
®
Spring-Set Disc Brakes P/N 8-078-889-00
effective 01/04/13
Installation and Service Instructions for 320 Series
AAB Spring-Set Brakes
Important
Please read these instructions carefully before installing,
operating, or servicing your Stearns brake. Failure to
comply with these instructions could cause injury to
personnel and/or damage to property if the brake is
installed or operated incorrectly. For definition of limited
warranty/liability, contact Rexnord Corporation, Stearns
Division, 5150 S. lnternational Dr., Cudahy, Wisconsin
53110, (414) 272-1100.
OEM’s and subsystem suppliers, please forward these
instructions with your components to the final user.
Caution
1. Servicing shall be in compliance with applicable local
safety codes including Occupational Safety and Health
Act (OSHA). All wiring and electrical connections must
comply with the National Electric Code (NEC) and local
electric codes in effect.
2. To prevent an electrical hazard, disconnect power
source before working on the brake. If power
disconnect point is out of sight, lock disconnect in the
off position and tag to prevent accidental application of
power to system.
3. To avoid damage to internal power supply, hipot testing
should not exceed 1500 volts for one second. Brake
coil leads must be connected together.
4. Heat developed during normal operation (135°C) of the
brake may be hot enough to be painful or cause injury.
Be careful when touching exterior surfaces. Allow
sufficient time for the brake to cool before servicing.
5. After usage, the brake will contain burnt and degraded
friction material dust. This dust should be removed
before servicing or adjusting the brake.
DO NOT blow off dust using an air hose. It is important
to avoid dispersing dust into the air or inhaling it, as this
may be dangerous to your health.
a) Wear a filtered mask or a respirator while removing
dust.
b) Use a vacuum cleaner or a soft brush to remove
dust from the brake. When brushing, avoid causing
the dust to become airborne. Collect the dust in a
container, such as a bag, which can be sealed off.
Installation
The brake can be mounted on either face. With units
mounting on the hub end, the hub should be secured to
shaft before mounting brake. Two set screws are provided
and should be tightened securely. Refer to Table A for
set screw torque. The key should not extend towards the
armature or past the face of the hub. Refer to Table B or
C for positioning of hub. Mount brake to register using
screws or bolts. Refer to Table A for mounting torque.
Lock washers are optional. The rated voltage should be
available at the brake and allowance should be made
for voltage drop in long wiring runs. The optional, factory
installed, manual release lever is a rotary maintained
design.
Note: Position of hub should allow full engagement of
friction disc without interfering with the movement of
the armature. Motor shaft end float should be taken into
consideration when positioning the hub.
Table A
*An adapter plate is available for mounting on motors with four equally
spaced holes on a 2.844 inch bolt circle.
Table B
*This dimension is for units mounting on hub end, and using short
version of the hub. Factor in motor shaft end float; do not allow hub to
contact armature.
AngularParallel
.005.005.003 to .015.015*
See back page
.49
2.8
2.0
.005.005.003 to .015.015*.171.8
.005.005.003 to .012.015*.211.2
Maximum Allowed
Misalignment (inches)
Operating
Range
Air Gap
(inches)
X1
Hub
Position
(inch)
X
Size
Set Screw Torque Mounting Screws
AAB
Size Short
Hub Long
Hub Size
1.2
1.8
2.0*
2.8
9-10 lb-in
9-10 lb-in
9-10 lb-in
9-10 lb-in
9-10 lb-in
18-20 lb-in
18-20 lb-in
18-20 lb-in
#4
#6
#6
#8
Max
Torque Min
Req
11 lb-in
20 lb-in
20 lb-in
37 lb-in
3
2
3
2
Rexnord Corporation
Stearns Division
5150 S. International Drive
Cudahy, Wisconsin 53110
(414) 272-1100 Fax: (414) 277-4364 www.stearns.rexnord.com Copyright©1998-2013 by Rexnord Corporation
Repairs
The hub is the only replaceable item in this brake.
General
After proper installation, no further adjustment should be
required for the life of the unit.
Full rated torque of a new AAB brake may not develop
until the mating surfaces have been burnished or run-in.
Power supply
The voltage to be applied is determined by rating shown
on the nameplate. Resistance and other coil data for
various voltages are tabulated on appropriate Engineering
Data Sheets. This data can be secured by contacting the
factory.
Troubleshooting for AAB Brakes
Overheating, coil burned out or loss of torque
1. Check ambient temperature. It is above 40° C? Consult
factory for assistance.
2. Check thermal capacity of unit versus actual heat
dissipation requirements. Consult factory.
3. Check voltage supply as close to coil as feasible.
Compare to nameplate data, if incorrect apply proper
voltage.
4. Is coil resistance correct? Consult factory for resistance
of the specific coil.
Caution: To avoid damage to power supply, hipot testing
should not exceed 1500 volts for one second. Brake coil
leads must be connected together.
5. Stop time on brake normally should not exceed one
second. If excessive, recheck torque rating versus load
characteristics.
6. Check for oil/grease on friction elements. If this is
found, replacement of entire brake may be required.
7. On pressure spring, check for broken, missing or
substituted springs not of our design.
8. Failure to release after unit has performed satisfactorily
for a period indicates wear has occurred. Replacement
of the brake is required.
Fuse in DC power supply blows
1. Never put in a higher rating fuse or replace with a
slo-blow type.
2. Check resistance of coil, if shorted, replacement of
brake is required. If not shorted, obtain coil resistance
from factory and compare to your reading.
3. If cause was not found in Step 2 above, check rectifier
bridge by removing all loads and replacing fuse. If
fuse blows when AC is applied to rectifier, bridge is
shorted. Replace bridge if feasible or discard control
and replace.
Size
Hub
Position
(inch)
Operating
Range
Air Gap
(inches)
Maximum Allowed
Misalignment (inches)
XX
1Parallel Angular
2.8 .954 .050 .003 to .015 .005 .005
*Size 2.8 can be pressure plate mounted using the long hub.
