P/N 8-078-924-06
effective 2/23/04
®
Spring-Set Disc Brakes
Installation and Service Instructions
for 48,100 Series Brakes (rev. A)
(Models 1-048-151, 1-048-161 and 1-048-171)
Figure 1
4. Be careful when touching the exterior
of an operating brake. Allow sufficient
time for brake to cool before
disassembly. Surfaces may be hot
familiar with the construction and
operation of the brake.
Important
Please read these instructions carefully
before installing, operating, or servicing
your Stearns brake. Failure to comply with
8. For proper performance and operation,
only genuine Stearns parts should be
used for repairs and replacements.
enough to be painful or cause injury.
these instructions could cause injury to
5. Do not operate brake with housing
removed. All moving parts should be
guarded.
personnel and/or damage to property if
the brake is installed or operated
incorrectly. For definition of limited
warranty/liability, contact Rexnord
Industries, Inc., Stearns Division,
5150 S International Drive.,
General Description
The 48,100 series is a spring-set,
electrically released disc brake for
controlled stopping and holding of a load.
It has a single-phase solenoid coil for
operation on alternating current only. The
nominal static torque is factory set.
6. After usage, the brake interior will
contain burnt and degraded friction
material dust. This dust must be
removed before servicing or adjusting
the brake.
Cudahy, WI 53110, (414) 272-1100.
Caution
Construction
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.
1. Installation and servicing must be made
in compliance with all 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.
The 48,100 series brake utilizes one
composition friction disc driven by a metal
hub that is fastened to the motor shaft.
Manual release with automatic electrical
reset is provided. Splined hub and friction
disc is standard. Only open enclosure is
available.
a) Wear a filtered mask or a respirator
while removing dust from the inside
of a brake.
2. Do not install the brake in atmospheres
containing explosive gases or dusts,
corrosive substances, water, oil or dust.
Operation
When brake is properly wired, starting the
motor will energize the solenoid and
compress the pressure spring. This action
removes the force against the stationary
plate and friction disc and allows the disc
to rotate freely. Stopping the motor will de-
energize the solenoid and restores
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.
3. 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.
7. Installation and servicing should be
performed only by qualified personnel
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personnel or damage to equipment
before any disassembly of the brake is
attempted or before the manual release
lever is operated on the brake.
the screws and slide entire brake off
motor and hub.
wires positioned as before. Install
plunger guide(s) in reverse order of (4).
3. Remove housing support nut (19) and
solenoid mounting nut (19) from one
side of the solenoid mount. Slide
carriage bolt (sA) out the backside of
the endplate (2). Remove solenoid
spacer (3C) and shock pad (3G).
5A. For solenoid assembly replacement,
remove plunger screw (9) and plunger
nut (9B). Install new plunger (29A)
with new plunger screw and nut.
2. Observe all cautions listed at the
beginning of this manual before
attempting to service brake.
6. Reassemble brake in reverse order of
Steps 1, 2 and 3. Tighten solenoid
mounting nuts (19) to 15 lb-in of torque
to compress the shock pad (3G).
3. Remove housing screws (15) and
housing (7) or (7A).
4. Slide old friction disc out the side of the
brake assembly.
Wear adjustment
5. Insert new friction disc between
endplate (2) and stationary plate (5).
Reassemble brake in reverse order of
Steps 2 & 3. Tighten the solenoid
mounting nut (19) to 15 lb-in to
compress the shock pad (3G).
Note: If solenoid buzz is noted, readjust
solenoid mounting nut (19) to “tune out”
the buzz.
1. Normal friction disc wear will cause
solenoid air gap to become larger from
the original set 1/8” air gap. An
increase in stopping time and a slight
reduction in torque will consequently
occur. See Figure 6.
7. Reposition the housing support hot (19)
165" from the top of the housing bolt.
8. Replace housing.
Note: If solenoid buzz is noted, readjust
solenoid mounting nut (19) to “tune out”
the buzz.
2. When the solenoid air gap increases to
1/4”, the brake must be adjusted. The
gap is measured between the mating
ground surfaces of the solenoid frame
and solenoid plunger.
9. Restore power to brake.
VI. Troubleshooting
A. If brake does not stop shaft properly
or overheats, check the following:
6. See Wear adjustment. It may be
necessary to turn wear adjust screw
(10) CCW for clearance.
Note: To measure air gap on brakes
mounted vertical above motor, push
plunger into frame until spring pressure is
felt. Holding firmly in this position,
measure air gap between mating (ground)
surfaces on solenoid frame and solenoid
plunger. If adjustment is made, check air
gap by again holding plunger as directed.
7. Repostion the housing support hot (19)
165" from the top of the housing bolt.
1. Is brake manually released rather than
electrically released while motor is
running?
8. Replace housing.
9. Restore power to brake.
2. Is friction disc excessively worn,
charred, or broken?
Coil or solenoid assembly replacement
1. Disconnect coil (12C) from circuit.
3. Has hub become loose and shifted on
shaft?
3. To decrease air gap, turn the wear
adjusting screw (10) clockwise until an
air gap of 1/8” minimum is attained.
To increase gap, turn screw
2. Cut the plastic wire tie holding the coil
leads onto the housing stud (18).
4. Is hub clean, and does friction disc
slide freely?
3. Remove housing and solenoid
mounting nuts (19) and lift solenoid /
coil assembly off the mounting bolts.
5. Does stationary plate slide freely on
guide pins?
counterclockwise.
4. After adjustment, push in plunger and
allow it to snap out. Recheck air gap,
see Note.
6. Are pressure springs improperly
assembled, or broken?
4. Remove plunger guide (82A) by lifting
out of top of solenoid frame. Coil (12C)
has a lock tab, located at top of coil
opposite lead wire side, which is
pressed against coil and coil is slid
sideways from solenoid frame.
7. Is solenoid air gap adjusted correctly?
See Wear Adjustment.
5. Replace friction disc when wear area is
one half original disc thickness of 3/16”.
8. Does solenoid linkage move freely?
9. Is voltage supply at coil correct?
Friction disc replacement
5. For coil replacement, inspect and clean
solenoid assembly. Install the new coil
in original solenoid frame or original
coil in new solenoid frame with the lead
1. Disconnect power source to brake.
10. Are controls which govern start or
stop of braking cycle operating
properly?
2. Align friction disc (4) notches with the
two 1/4” flat head cap screws. Remove
Figure 6
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11. Is brake coil energized at same time
or prior to energization of motor, and
de-energized at same time or after
de-energization of motor?
8. Does solenoid linkage move freely?
9. Check for excessive voltage drop in
motor line when motor is started.
Check wire gauge of supply line
against motor starting current and
solenoid inrush current. Measure
voltage drop at solenoid coil leads
during maximum inrush current
condition. To accomplish this, connect
voltmeter at brake coil. Insert a block of
wood, or other non-magnetic material,
between solenoid plunger and frame.
Block thickness should approximately
equal solenoid air gap. Energize motor
and brake simultaneously, take reading
and immediately shut down. (This is to
prevent motor, brake, or solenoid burn
up, since brake will be set during
procedure.)
12. Is stopping time more than one
second (rule of thumb) and/or is
application more than five stops per
minute? If so, consult factory. Check
thermal requirements of load versus
thermal rating of brake.
13. Replace friction disc when worn area
is one half of original thickness of
3/16”.
B. If brake hums, solenoid pulls in
slowly, or coil burns out, check the
following:
1. Voltage supply at coil versus coil rating
and connection.
C. If disc noise occurs, check:
2. Is solenoid air gap excessive?
3. Shading coils may be broken.
1. If friction disc (4) becomes noisy, check
stabilizing spring (4A) to be sure it is
installed.
4. Plunger guides may be excessively
worn. Does solenoid plunger rub on
solenoid frame laminations?
2. Check that the leaf spring (5A) is
supporting stationary plate (5). If
distorted, replace.
5. Solenoid frame and plunger may be
excessively worn.
6. Is solenoid dirty?
7. Housing studs may have become loose
causing frame to shift and plunger to
seat improperly.
Copyright© 2000 by Rexnord Industries, Inc.
Rexnord Industries, Inc., Stearns Division, 5150 S. International Drive, Cudahy, Wisconsin 53110
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