Stearns 1-048-171, 1-048-161, 1-048-151 User Manual

®

Spring-Set Disc 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
Industries, Inc., Stearns Division,
5150 S International Drive.,
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,
corrosive substances, water, oil or dust.

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. 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.

5. Do not operate brake with housing
removed. All moving parts should be
guarded.

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.

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.

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.

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.

Construction

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.

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 de­energize the solenoid and restores

Figure 1

Installation and Service Instructions
for 48,100 Series Brakes (rev. A)

(Models 1-048-151, 1-048-161 and 1-048-171)

P/N 8-078-924-06

effective 2/23/04

pressure spring force against the
stationary plate and friction disc, stopping
and holding the load.

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.

When the motor is off and the load is to
be moved without energizing the motor,
the manual release lever can be rotated
90° away from the mounting face. This
removes the retarding torque from the
motor shaft, allowing the load to be
moved. The brake will remain in the
manual release position until the release
lever is returned manually to its

set

position, or until the brake is re-energized
electrically and the release lever 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.

I. General Installation Notes

Brake mounting can be in any position.
Brake is mounted with two 1/4” flat head
socket cap screws mounted 180° apart.

II. Installation Procedure

1. Remove housing nuts (15) and housing
(7) or (7A).

2. Remove hub (16) from brake and slide
onto motor shaft and key (not
furnished) to within 3/16” of motor
mounting surface. Torque both set
screws to 33 lb-in of torque.

Note: Check motor mounting face 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”.

3. Attach brake to mounting surface by
sliding the brake friction disc (4) onto
hub (16), engaging without force. Brake
endplate (2) is to be tight against
mounting face.

4. Mounting the brake to the mounting
surface with two 1/4” flat head socket
cap screws (not furnished). Notches
are provided in the friction disc for
accessibility to the mounting holes.
Torque to screw manufacturer’s
recommendation based on materials
being used. Screw heads may not
protrude above wear surface. Brake
mounting can be in any position.

5. Verify solenoid air gap is 1/8”. Push in
plunger and allow it to snap out. Check
air gap. For vertical above motor
mounting, see Note in

Wear

Adjustment

Section. If adjustment is

required, see

Wear Adjustment.

6. See

Electrical Connection

for coil

connection.

7. Replace housing.

III. Torque Adjustment

The brake is factory set for nominal rated
torque. No further adjustment to increase
torque may be made. The approximate
compressed torque spring length to
produce nominal rated torque is given in
Table A.

To increase stopping time on 3 and 6 lb-ft
brake, turn torque adjusting nuts (18)
counterclockwise equal amounts to
increase spring length. Spring studs
equipped with flats on the end are for a
wrench if the studs loosen during torque
adjustment. For the 3 and 6 lb-ft brakes,
one full turn on the nut will reduce the
nominal torque approximately 15%. Do
not reduce torque to less than 50% of
nominal rated. Torque for the 1.5 lb-ft
brake may not be reduced.

IV. Electrical Connection

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 motor 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.

General

All coils are single-phase alternating
current (AC).

Single voltage coil connection

Connect coil (12C) to any two wires of a
single-phase or three-phase power source
of appropriate voltage. For operation with
a motor control, connect to any two motor
leads with correct voltage.

Dual voltage coil connection

Preconnect coil for appropriate high or
low voltage as shown in Figure 3. On
these coils observe the lead numbering
sequence for proper connections as
follows:

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 4 or 5, the motor can be operated
on either 230 volts or 460 volts with no
effect on brake operation.

V. General Maintenance

1. Warning! Any mechanism or load held
in position by the brake should be
secured to prevent possible injury to

Table A

Brake Torque

(lb-ft)

Length “L”

(in.)

1.5
3
6

1

15/16

1-1/8

1-1/2 and 3 lb-ft

6 lb-ft

Figure 2

Figure 3

3 and 421High voltage

–2 and 41 and 3Low voltage

Tie Leads

Power Line BPower Line A

For

Figure 4 Figure 5