Stearns 500 User Manual
the point where spring pressure is felt,
before measuring solenoid air gap.) As
friction disc wear occurs, the air gap will
increase as well as stopping time. If
solenoid air gap exceeds 11/16”,
adjustment is necessary.
before measuring solenoid air gap.) As
friction disc wear occurs, the air gap will
increase as well as stopping time. If
solenoid air gap exceeds 11/16”,
adjustment is necessary.
2. The solenoid air gap may be decreased
by turning both wear adjustment screws
(10) equal amounts clockwise,
approximately 1/8 turn, until solenoid gap
is attained. Counterclockwise rotation will
increase gap.
(10) equal amounts clockwise,
approximately 1/8 turn, until solenoid gap
is attained. Counterclockwise rotation will
increase gap.
3. Follow Step 1 and Step D of
Installation
Procedure, Section I, to replace housing.
4. Restore power source to brake.
B. Replacement of friction discs
Follow Steps B-1, 2, 5, 6 and D of
Installation Procedure, Section I.
Installation Procedure, Section I.
C. Inspection or replacement of solenoid
and associated components
and associated components
1. Refer to Figures 8 and 9. Insert
screwdriver between support plate (126)
and lever arm (17). Wedge apart and
remove as an assembly bearing pin (26),
bearing (6), pin (131), solenoid lever (8)
connected to solenoid link (13) and
plunger (29).
and lever arm (17). Wedge apart and
remove as an assembly bearing pin (26),
bearing (6), pin (131), solenoid lever (8)
connected to solenoid link (13) and
plunger (29).
2. On coil type (12A) remove plunger guide
screw and lock washer. Remove both
plunger guides (82) by prying up on the
flanges. Slide coil (12A) sideways from
frame noting position of coil terminals or
lead wires.
plunger guides (82) by prying up on the
flanges. Slide coil (12A) sideways from
frame noting position of coil terminals or
lead wires.
a) On coil type (12B), remove plunger
guide (82A) by lifting out of top of
solenoid frame. Coil (12B) has a lock
tab, located at bottom of coil opposite
lead wire side which is pressed against
coil and coil is slid sideways from
solenoid frame.
solenoid frame. Coil (12B) has a lock
tab, located at bottom of coil opposite
lead wire side which is pressed against
coil and coil is slid sideways from
solenoid frame.
3. Inspect and clean all items. If coil, plunger
guides, or solenoid replacement is
required, refer to appropriate replacement
parts list and select necessary
replacement part, kit or assembly. Kits or
assembly packets contain full retrofit
instructions.
required, refer to appropriate replacement
parts list and select necessary
replacement part, kit or assembly. Kits or
assembly packets contain full retrofit
instructions.
4. Reassemble brake in reverse order of
Steps 1 and 2.
5. Replace housing.
6. Restore power source to brake.
D. Miscellaneous parts replacement
(see Figures 1 and 8)
(see Figures 1 and 8)
All parts shown in Figures 1 and 8 are
available as kits, assemblies, or piece parts.
Consult appropriate parts list for ordering
information. Kits and assembly packets
contain complete repair instructions.
available as kits, assemblies, or piece parts.
Consult appropriate parts list for ordering
information. Kits and assembly packets
contain complete repair instructions.
V. Troubleshooting
A. If brake does not stop properly or
overheats, check the following:
overheats, check the following:
1. Are friction discs excessively worn,
charred, or broken?
2. Hub may have become loose and
shifted on shaft. Recheck Section I,
appropriate Step.
appropriate Step.
3. Is hub clean, and do friction discs slide
freely?
4. Do stationary discs slide freely in the
endplate? Check slots of endplate for
wear at the areas where stationary discs
are in contact. Grooves in the slots can
cause hang-up of ears of stationary
discs. If grooving is noted, replace
endplate.
wear at the areas where stationary discs
are in contact. Grooves in the slots can
cause hang-up of ears of stationary
discs. If grooving is noted, replace
endplate.
5. On vertically mounted brakes, are
springs in place in disc pack? See Sheet
301.4 for 55,000; 55,300; 55,400 and
57,500 or Sheet 301.5 for 55,300 and
55,500 if correct sequence is in doubt.
301.4 for 55,000; 55,300; 55,400 and
57,500 or Sheet 301.5 for 55,300 and
55,500 if correct sequence is in doubt.
6. With brake de-energized and housing
(7) removed, check compressed length
of pressure springs (11). Compare to
tabulated values and adjust to minimum
height to obtain desired stop times. See
Torque Adjustment, Section III, Table 1.
of pressure springs (11). Compare to
tabulated values and adjust to minimum
height to obtain desired stop times. See
Torque Adjustment, Section III, Table 1.
7. Is solenoid air gap adjusted correctly?
See Section IV and refer to
Air Gap
Setting, Table 2.
8. Solenoid may not be energizing and
releasing the brake. Check voltage at
the coil and compare to the coil and/or
nameplate voltage rating.
the coil and compare to the coil and/or
nameplate voltage rating.
9. 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.
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.
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.
10. If brake is DC solenoid style, check
switch actuation and condition of coil.
The switch should open with a 3/16”
approximate air gap. (This is plunger
The switch should open with a 3/16”
approximate air gap. (This is plunger
travel remaining before plunger seats to
frame.)
frame.)
11. Check linkage for binding. The
approximate pressure applied to the top
of the solenoid link to move plunger is:
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.
cause of binding and correct. Do not
overlook bent, worn or broken plunger
guides as a possible cause for binding.
12. Are controls which govern start of
braking cycle operating properly?
13. Brake coil should be energized at same
time or prior to energization of motor,
and de-energized at same time or after
de-energization of motor.
and de-energized at same time or after
de-energization of motor.
14. If stopping time is more than 1 second
(rule of thumb) and/or application is
more than five stops per minute, check
thermal requirements of load versus
thermal rating of brake.
more than five stops per minute, check
thermal requirements of load versus
thermal rating of brake.
15. Check mounting face to which brake is
attached per
Installation Procedure,
Note 2 after Item 1.
16. Replace friction disc(s) when worn area
is one half of original thickness (3/16”).
17. Check to be sure wear adjust screws
are of equal height. Measure from
inboard side of support plate with depth
micrometer. Turn one screw to obtain
equal height, reassemble and see
Adjustment for Friction Disc Wear.
inboard side of support plate with depth
micrometer. Turn one screw to obtain
equal height, reassemble and see
Adjustment for Friction Disc Wear.
B. If solenoid hums, pulls in slowly, or
coil burns out, check the following:
coil burns out, check the following:
1. Check A-6 through A-11 of this Section.
2. Check for broken shading coil.
3. Plunger guides may be excessively worn.
Does solenoid plunger rub on solenoid
frame laminations?
frame laminations?
4. Solenoid frame and plunger may be
excessively worn.
5. Is solenoid dirty?
6. Solenoid mounting screws may have
become loose, causing frame to shift and
plunger to seat improperly.
plunger to seat improperly.
142 139W 139S 139 3 142S 4 16 161 16S 2
57,500 16A 16S 4A 16B 16S 4B
Figure 9
5 lbs
#K4 coil
3-1/2 lbs
#4 coil
Copyright© 1997 by Rexnord Industries, Inc.
Rexnord Industries, Inc., Stearns Division, 5150 S. International Dr., Cudahy, Wisconsin 53110, (414) 272-1100 Fax: (414) 277-4364