Stearns 87,700 Series Quick guide

®
Spring-Set Disc Brakes
P/N 8-078-927-07
effective 5/15/97
Installation and Service Instructions for
87,700 Series Double C-Face Coupler Brake
Figure 1
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 Industries, Inc., Stearns
Division, 5150 S. International Dr., Cudahy, WI
53110, [phone].
Caution
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.
2. Do not install the brake in atmospheres
containing explosive gases or dusts.
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.
4. Make certain power source conforms to the
requirements specified on the brake
nameplate.
5. Be careful when touching the exterior of an
operating brake. Allow sufficient time for
brake to cool before disassembly. Surfaces
may be hot enough to be painful or cause
injury.
6. Do not operate brake with housing removed.
All moving parts should be guarded.
7. Installation and servicing should be
performed only by qualified personnel
familiar with the construction and operation
of the brake.
8. For proper performance and operation, only
genuine Stearns parts should be used for
repairs and replacements.
9. After usage, the brake interior will contain
burnt and degraded friction material dust.
This dust must 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 from the inside of a brake.
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.
General Description
The 87,700 Series coupler is a spring-set,
electrically released, self adjusting brake. The
double C-face allows the brake to directly
couple a C-face motor to a C-face gear
reducer. Or, for in-line application, the brake
can be mounted directly to a foot mounted
C-face motor, using the bearing mounted
output shaft as an in-line drive shaft.
Note: Coupler brake is designed for in-line
applications only. Do not apply overhung or
side load to brake output shaft.
Operating Principle
The 87,700 Series brake utilizes one, two or
three rotating friction discs driven by a hub
which is mounted on the motor shaft. The
solenoid air gap is factory set, and normally
requires no resetting even when changing
friction discs. A wrap spring clutch permits the
solenoid air gap to be adjusted automatically to
compensate for friction disc wear or normal
expansion.
When brake is wired into motor circuit, starting
the motor will energize the solenoid and
compress the pressure spring. This action
removes the force against the disc pack
components and allows the friction discs to
rotate freely. De-energizing the motor de-
energizes the solenoid and restores pressure
spring force against the disc pack, thereby
stopping and holding the load.
When the motor is
off and the load is to be
moved without energizing the motor, the
manual release lever should be used. This
removes the holding torque from the motor
shaft, allowing it to be rotated by hand,
however drag may be noted. The brake will
remain in the manual release position until the
release lever is returned manually to their
set
position or until the brake is re-energized
electrically and the release lever or rod returns
to its set position automatically.
Note: The motor should not be run with the
brake in the manual release position to avoid
overheating of friction disc(s).
I. Installation Procedure
Note 1: Check face of motor to which brake is
to be mounted, to be sure NEMA dimensions
of 0.004” T.I.R. on concentricity and face run
out are met. Shaft run out is to be within 0.002”
T.I.R. Maximum shaft end float is 0.020”. Use
standard length NEMA shaft.
Note 2: The effectiveness of the dust-tight
waterproof brake enclosure depends on a fully
enclosed motor C-face as the brake face is not
sealed.
A. Remove hub (16) from brake assembly.
With key (not furnished) in place on motor
shaft, slide hub (square, or splined, end
first) onto shaft to 1” (± 1/32”) of standard
24 tooth 4.24 diameter16 tooth 3.12 diameter
Splined Configurations

motor C-face. Securely tighten both set
screws to 156 in-lbs on 5/16” and 290 in-lbs
on 3/8”.
Note 3: On most applications, particularly in
vertical position, a set screw dimple drilled into
shaft is recommended.
B. Remove housing bolts (15), lock washers
(15W) and housing (7).
C. Depress solenoid plunger (29) and tie
plunger to frame (79).
D. Remove entire support plate assembly (142)
by evenly unscrewing screws (142S).
Remove screws, conical spring washers
(142W), and flat washers (142X).
E. Remove pressure plate (5), friction disc (4)
and stationary disc (3).
Note 4: Brakes with a single friction disc do
not have stationary discs. Vertically mounted
brakes will have special pins which hold spacer
springs and, in some cases, spring washers
(except one disc vertical below). Note color
coded sequence of springs and location of
washers, if used, or refer to Sheet 301.3 for
proper assembly of vertical mounting
components.
F. Attach endplate (2) to NEMA C-face of motor
using four 1/2-13 socket head cap screws
and medium spring lock washers (not
supplied) torque per manufacturer’s
specifications. (Head of cap screws must not
project above friction surface.)
Note 5: If motor, with or without reducer, is to
be ceiling mounted after assembly, entire brake
will have to be rotated 180° or “upside down”
so it will be positioned with solenoid plunger
(29) above frame when final assembly is
mounted on ceiling. Similarly, for horizontal wall
mounting, rotate 90°.
G. Reassemble friction discs (be sure friction
discs slide freely, file I.D. if necessary),
springs (if vertical), stationary discs, and
pressure plate in correct sequence and
position. All parts must slide freely. The
universal mounting pressure plate presently
used has three tapered reliefs on outboard
face. However, some older brakes used a
pressure plate with a single tapered relief
marked
top , which must be installed with
relief in area of sector gear (31).
H. Mount support plate assembly, torque
screws to 50 in-lbs in endplate. Conical
spring washer installed under the screw
head. Flat washer used under the conical
spring washer only with aluminum support
plate. Be sure that assembly is mounted
with the solenoid in a vertical position
(plunger above frame) as shown when
brake is horizontal. If plunger is not tied
down and has allowed the mechanism to
overadjust, it will have to be reset before
mounting support plate. In this case the
lever arm (17) throat will be near, or
touching, the pinion (32) teeth. Refer to
Figure 6 and
Self-Adjust Maintenance .
Loosen pressure spring cap screw (19) until
pressure spring (11) is free, mount support
plate assembly to endplate, and retighten
spring cap screw until snug. Do not
overtighten! Torque to a maximum of
100 in-lbs.
I. Remove plunger tie-down. Manually lift
solenoid plunger to maximum travel and
release. Complete electrical connections,
(See Section on
Electrical Connection of
Brake
.) Depress solenoid plunger manually
or electrically, and allow it to snap up.
Repeat this process several times to set air
gap on solenoid. (Check
Self-Adjust
Maintenance Section for proper gap
measurement, or corrective action for
improper gap.)
J. See Section on
Electrical Connection of
Brake , Note 2.
K. Assemble housing and shaft assembly,
rotating shaft (35) to engage key (35K) into
hub keyway. Be sure housing is assembled
with manual release on right hand (solenoid)
side (looking at output shaft side) or release
lever (148) will not latch. Replace housing
bolts and tighten evenly to 118 lb-ft of
torque.
L. For reducer application, mount and secure
brake/motor combination to mounting face
of reducer.
For alignment when brake shaft is direct-
connected to another shaft by a coupling
refer to coupling manufacturer’s suggested
procedure. Side or overhung load is not
permitted. Consult factory for reversing
applications.
II. Electrical Connection of Brake
CAUTION 1: Inverter Motor and Special
Control Systems. This brake contains either a
single phase AC coil or DC coil that requires
instantaneous power within ± 10% of rating at
the coil. A separate power source is required
when this brake is used in conjunction with a
motor or control system that limits voltage or
current input (i.e. inverter motors) or causes a
ramping of the power supply.
CAUTION 2: Class H coils with terminals. Do
not bend lead wire crimp connection as this
causes a fatigue in the metal which may break
under vibration.
Note 1: Brake coil connections described here
cover common motor connections. For
nonstandard motors or control connections,
contact respective supplier or Stearns Division.
Note 2: Be sure lead wires to coil are not tight
or pinched, and that leads will not be rubbed
by friction disc, trapped between solenoid
plunger and frame, caught between lever arm
and endplate, or by linkage.
Note 3: On brakes with space heater, connect
to appropriate power source. Heater is to be
energized continuously, including storage
periods, if rust may occur.
A. AC coils, single voltage
1. Dual voltage coils may be factory
preconnected for high voltage unless
otherwise specified on brake purchase
order. Checking coil connection is
suggested.
2. On single voltage coils, connect coil to any
two leads on single or three-phase motors
of the same voltage as the brake. Refer to
brake nameplate and coil number for correct
voltage and frequency. See Figure 2 for dual
voltage coil connection and connect to any
two leads of single or three-phase motor of
the same voltage. The brake can also be
wired to external switch contacts providing
proper voltage other than that used to
control the motor. Normally, the motor and
brake contacts are interlocked.
B. Connecting AC solenoid coils on dual
voltage 230/460 three-phase motors
To use a 230 volt coil (or a 230/460 dual
voltage coil connected for 230 volts) with a
230/460 dual voltage three-phase motor, the
brake leads are connected across two motor
terminals as shown, or other equivalent
combinations. If a 230 volt brake coil is
connected as shown in Figures 3 and 4 the
motor can be operated on either 230 volts or
460 volts with no effect on brake operation.
C. DC coils - all models
1. All Stearns DC coils are single voltage dual
winding. A high current pull-in winding is
initially energized to start the plunger
movement, while a low current holding
winding is momentarily shunted from the
circuit until the plunger has pulled in. The
older design incorporated a mechanical
switch mounted to the solenoid frame and
actuated by an arm mounted to the plunger
to bring the holding winding into the circuit.
In addition, coils over 48 Vdc have an arc
suppression module in parallel with the
switch contacts to protect the contacts from
arc erosion and suppress EMI. The polarity
of the incoming power supply is immaterial
with the mechanical switch. The new
electronic switch design incorporates an
electronic timing circuit to allow the plunger
to pull in, then electrically switch to the
holding winding. Polarity of the power supply
to the electronic switch and coil must be
maintained. Refer to Figure 5 for proper
wiring.
Caution! Never use a series resistor to
drop power supply voltage to the coil as
brake malfunction will result.
2. Due to high initial current demands of a DC
solenoid, a separate DC power source of
adequate current capacity is usually
required.
Caution! For electrical release of brake,
apply full rated coil voltage instantly. Do not
increase voltage slowly.
AC Voltage Coil Connection
Figure 2
3 and 421High voltage –2 and 41 and 3Low voltage Tie Leads
Power Line BPower Line A For
Class B Coil (black)Class H Coil (colored)
Figure 3 Figure 4

III. General Maintenance
Warning! Any mechanism or load held in
position by the brake should be secured to
prevent possible injury to personnel or damage
to equipment before any disassembly of the
brake is attempted or the manual release lever
is operated on the brake. Observe all
cautions
listed at the beginning of this manual.
Note 1: Replacement part kits for many items
are available and contain retrofit instructions.
Note 2: Do not lubricate any part of the brake
as this may cause a malfunction and/or loss of
torque.
A. Coil replacement
All standard NEMA AC voltage coils are
available in kits. Select coil kit from appropriate
replacement parts list for the particular brake
series being serviced.
All standard NEMA DC voltage coils are
available in assemblies and may also be
obtained from appropriate parts list.
B. Friction disc replacement
Note: Replace friction discs in single disc
brakes when wear surface area is one half the
original disc thickness (1/4”). In multiple disc
brakes, replace all friction discs when throat of
lever arm (17) is within 1/16” of touching teeth
of pinion (32).
1. Replacement friction discs for use with either
square or splined brake hubs are available
in kits. Select applicable kit from appropriate
parts list for the brake being serviced.
2. If brake uses metal carrier rings with bonded
friction linings (P/N 5-18-7001-00) for use
with splined hub obtain required quantity.
Then proceed as follows:
a) Observe cautions and warnings
preceding
Installation Procedure ,
Section I. Follow Steps L and K then
disconnect solenoid lead wires.
b) Continue with Steps C through E and
Steps G through L. Be sure to reconnect
coil leads before replacing housing (7).
C. Other standard replacement parts
The standard 87,700 Series brakes use
replacement part kits or components
depending on the items involved. Consult Parts
List P/N 8-078-917-07 (Sheet 366) for material
needed.
D. Self-adjust maintenance
(See Figure 6)
Since the self-adjust brake automatically
adjusts itself for friction disc wear, maintenance
is held to a minimum. The solenoid is factory
set with a 13/16” to 15/16” air gap, and
requires no resetting, even when changing
friction discs. The gap is determined by the
position of wrap spring stop (76). Should air
gap change, follow the steps listed below:
1. If (stop) screws (76S) had been loosened
and retightened, the air gap may require
resetting. The gap is measured between
mating surfaces of plunger (29) and solenoid
frame (79), and may be increased by raising
slightly, or decreased by lowering slightly,
wrap spring stop (76). Be sure to retighten
(stop) screws (76S). Manually lift plunger to
maximum travel and release. Depress
plunger, manually or electrically, and allow it
to snap up. Repeat several times, then
recheck air gap for factory setting of 13/16”
to 15/16”.
Note: To measure solenoid air gap on
vertically mounted brakes, grasp solenoid
link to hold plunger in a free horizontal
position and move toward solenoid frame
until spring pressure is felt. Holding firmly in
this position measure air gap between
mating (ground) surface on solenoid frame
and solenoid plunger. Adjust to proper gap
as directed in
Self-Adjust Maintenance .
Check gap by again holding plunger as
directed.
2. Tang of wrap spring (71) must be below, and
must make contact with, wrap spring stop
(76) when solenoid lever (28) is manually
raised. If stop is bent outward, allowing tang
to bypass it, rebend to square position,
assemble correctly, and reset solenoid air
gap as described in Paragraph 1.
3. Should air gap have decreased or
disappeared, the solenoid lever and pinion
assembly (8) may have become
contaminated due to lubrication or residue
as a result of overheating of brake. Cleaning
is required. Loosen pressure spring nut (19)
until pressure spring (11) is free. Remove
support plate assembly (142). Remove
cotter pin (8P) from solenoid lever (28) and
retaining ring (131R) from pivot pin (131).
Note location of spacer washer (138) if used,
and push pivot pin out to free affected
assembly. Remove retaining ring (32R) from
pinion (32) and disassemble. Parts should
be thoroughly cleaned in a clean solvent that
does not leave a film M.E.K. or equivalent.
Dry all parts thoroughly
and reassemble. Rotate
pinion and wrap spring
clockwise until tang (A)
is aligned with
centerline of the upper
hole of the lever arm.
Refer to Figure 7.
Reassemble in reverse
order of Steps in this
Paragraph. Do not
retighten cap screw (19)
until support plate
assembly is mounted on endplate. Refer to
Steps H and I of
Installation Procedure to
complete assembly.
4. Check condition and positioning of pinion
(32) and rack (part of lever arm assembly
Figure 6
DC Voltage Coil Connection
Figure 5
*Arc suppression used for coil above 48 Vdc.
**Follow polarity for switch to operate.
Electronic Switch** (New Style)
Mechanical Switch (Old Style)
Class BClass H
Figure 7

[17]). Replace parts as necessary with
complete assemblies.
E. Solenoid lever and pinion assembly
replacement
If pinion (32) teeth are worn, replace entire
assembly (8). Consult appropriate parts list for
kit number. Check sector gear of lever arm (17)
for wear.
If sector gear teeth of lever arm (17) are worn,
replace entire lever arm assembly available as
a kit from appropriate repair parts list. Also
check pinion (32) teeth for wear. See Item 8.
F. Pressure spring stud and nut
replacement
On older designs of these brakes, item (152)
was a threaded shoulder stud nut (19), item
(152P) was a solid pin. These items have been
replaced by a spring tube, cap screw and
spring pin. Replacement of any individual
component requires replacement of all three
older style components. Consult appropriate
repair parts list for complete retrofit kit.
IV. Troubleshooting
A. If brake does not stop properly or
overheats, check the following:
1. Is manual release engaged, and is motor
energized?
2. Friction discs may be excessively worn,
charred or broken.
3. Hub may have become loose and shifted
on shaft.
4. Is hub clean and do friction discs slide
freely?
5. Are controls which govern start of brake
cycles operating properly?
6. Are limit switches, electric eyes, etc.
functioning properly?
7. On vertically mounted brakes, are
springs in place in disc pack? See P/N
8-078-937-05 (Sheet 301.3).
8. Have mounting faces loosened?
9. Pressure spring may be improperly
assembled or broken.
10. Is solenoid air gap adjusted correctly? (See
Self-Adjust Maintenance , Section III,
Item D.)
11. Check linkage for binding. The approximate
pressure applied to the top of the solenoid
link to move plunger is:
If excessive force is required, determine
cause of binding and correct. Do not
overlook bent, worn or broken plunger
guides as a possible cause for binding.
12. Solenoid lever stop (22) must be in place
on support plate.
13. Solenoid may not be energizing and
release the brake. Check voltage at the coil
and compare to the coil and/or nameplate
voltage rating.
14. Whether brake is AC or DC a voltage drop
may be occurring. If excessive drop in
voltage is noted, check wire size of power
source. Correct as needed.
Note: A method to check voltage at coil is
to insert a block of wood of the
approximate thickness of the solenoid air
gap between the solenoid frame and
plunger. (The block will prevent brake from
releasing when coil is energized.) Connect
voltmeter leads at the coil terminals or lead
wires. Energize coil. Voltmeter needle will
not fluctuate and reading can be taken.
Reading should be taken immediately and
the coil de-energized to prevent
overheating of the coil. Compare voltage
reading with coil rating.
15. If brake is DC solenoid style, check switch
actuation and condition of coil. The switch
should open with the following approximate
air gap. (This is plunger travel remaining
before plunger seats to frame.) Solenoid
size is used for reference.
If actuating arm is bent, replace plunger.
Check switch contacts. If pitted, replace
switch.
16. Check slots of endplate for wear at the
areas where stationary discs are in contact.
Grooves in the slots can cause hang-up or
even breakage of ears of stationary discs.
If grooving is noted, replace endplate.
17. Check that heads of mounting bolts do not
extend above wear surface of endplate.
18. On vertical above brakes, check the
vertical mounting pins to be sure shoulder
of pin is flush with wear surface of
endplate. Be sure pins are straight and the
pressure plate and stationary disc(s) are
free to slide on the pins. Be sure springs
and spacers are installed in proper order.
See P/N 8-078-937-05 (Sheet 301.3)
19. Check pressure spring length to insure
correct compressed height. Approximate
original spring lengths are given in the
following table so that correct setting may
be verified and corrected if necessary. With
worn friction discs, add amount of wear to
the approximate spring length shown in
table.
20. If a heater is supplied and excess rusting
has occurred in brake, check power source
to heater to be sure it is operating and that
heater is not burned out.
21. If stopping time is more than two seconds
(rule of thumb) and/or the application is
more than five stops per minute, check
thermal requirements of load versus
thermal rating of brake.
22. Use Loctite®242 to secure link screw nut
(13N) to link screw (13C) if vibration
causes nut to loosen.
B. If brake hums, solenoid pulls in
slowly, or coil burns out, check the
following:
1. Voltage supply at coil versus coil rating.
2. Is solenoid air gap excessive? (See Self-
Adjust Maintenance .)
3. Shading coils may be broken.
4. Plunger guides may be excessively worn.
Does solenoid plunger rub on solenoid
frame laminations? If so, replace plunger
guides.
5. Solenoid frame and plunger may be
excessively worn.
6. Is solenoid dirty?
7. Solenoid mounting screws may have
become loose, causing frame to shift and
plunger to seat improperly.
8. Sector gear and pinion teeth may be
jamming due to excessive tooth wear.
9. Excessive voltage drop when motor starts.
Check size of lead wires for motor starting
current and solenoid inrush current. See
Section IV-A, Item 11, 12, 14 and 15.
C. If brake is noisy during stopping:
1. Check mounting face run out, mounting
rabbet eccentricity and shaft run out. See
Installation Procedure , Section I, Note 1.
Correct as required.
2. Check for signs of the outside diameter of
the friction disc(s) rubbing on the inside
diameter of the endplate. This would indicate
brake is eccentric with respect to the motor
shaft and/or the shaft is deflecting during a
stop. Check alignment and shaft diameter.
Also check for worn motor bearings. If
realignment does not correct the problem, a
larger diameter shaft may be required. Shaft
deflection may also be caused by excessive
overhang of brake from motor bearing.
Additional shaft support may be required.
3. In cases where motor shaft extends through
a fan casing or guard, the clearance hole
may not be adequate. Rubbing of the shaft
may occur causing a noise during a stop. If
required, enlarge clearance hole.
4. Check for bad motor bearings. Replace if
necessary. Check for excessive shaft
endfloat. Correct as required.
Copyright© 1997 by Rexnord Industries, Inc. www.rexnord.com
Rexnord Industries, Inc., Stearns Division, 5150 S. International Dr., Cudahy, Wisconsin 53110, [phone] Fax: [phone]
16 lbs#8 coil 9 lbs#6 coil (25 lb-ft) 5-1/2 lbs#6 coil (15 lb-ft) 3 lbs#5 coil
#5 or 8 solenoid 3/16” to 7/32”
#6 solenoid 7/32” to 1/4”
Color Torque (lb-ft) Compressed
Spring Length
Blue or Black 6 3-1/2”
Blue 10 3-5/16”
Yellow 15 3-9/16”
Red 25 & 50 3-3/8”
Green 35, 75 & 105 3-3/8”
Black 10 3-1/4”
White 15 3-1/4”
Orange 25 & 50 3-1/4”
Purple 35, 75 & 105 3-1/4”