Stearns 1-056-X00 Torque Adjustment, Troubleshooting, Coil Failure, Excessive Wear / Overheating

TORQUE ADJUSTMENT

Torque Adjustment					TABLE A
Brake is factory set for nominal rated static		11		11	Nominal	Original	Maximum	% Torque
					Static	Spring	Counter-	Reduction
torque which is maximum torque. Torque
					Torque	Height	clockwise	per
may be decreased up to 50% for increased					(lb-ft)	(inches)	Turns	Turn
stopping times up to 2 second stop time.
					1-1/2	1.56”	-	-
The torque on the 1-1/2 lb-ft brake may not					3	1.50”
be reduced.	10			10	6	1.50”
Turn both spring adjustment screws (11),					10	1.56”	5-1/2	9%
Figure 6, equal amounts counterclockwise					15	1.56”
to decrease torque. See Table A for torque			Figure 6		20	1.56”
reduction permissible amounts.
					25	1.50”

TROUBLESHOOTING

COIL FAILURE

SUPPLY VOLTAGE CAUSE	SUPPLY VOLTAGE CORRECTION
Line voltage >110% of coil rating	Reduce voltage or replace with
	proper rated coil
AC input on a DC coil	Replace rectifier or replace with
	proper rated coil.
Excessive voltage drop during	Increase current rating of power
inrush time	supply.
WIRING CAUSE	WIRING CORRECTION
Leadwires interfering with plunger	Reroute wiring away from plunger
pull-in	and other moving components.
Excessive voltage drop during	Increase leadwires size from power
inrush time	supply
Coil leadwire shorted to ground	Replace coil or leadwire and protect
	with wire sleeving
SOLENOID ASSEMBLY CAUSE	SOLENOID ASSEMBLY
	CORRECTION
Plunger not seating flush against	Loosen solenoid mounting screws
solenoid frame	and reposition frame to allow full
	face contact
Plunger cocked in coil preventing	Realign solenoid frame
pull-in
Excessive solenoid/plunger wear	Replace solenoid assembly
at mating surface
Broken shading coils	Replace solenoid assembly
WORN PARTS CAUSE	WORN PARTS CORRECTION
Excessive wear of solenoid link	Replace link arm and link bolt; also
arm and/or shoulder bolt	inspect plunger thru-hole for
	elongation
Plunger guides worn down and	Replace guides
interfering with plunger
movement
APPLICATION CAUSE	APPLICATION CORRECTION
Machinery cycle rate is exceeding	Reduce brake cycle rate or use
brake rating	alternate control method
High ambient temperature	Use Class H rated coil and /or find
(>110%) and thermal load	alternate method of cooling brake
exceeding coil insulation rating
Brake coil wired with windings of	Wire coil to dedicated power source
an Inverter motor or other	with instantaneous coil rated voltage
voltage/current limiting device
MISCELLANEOUS CAUSE	MISCELLANEOUS CORRECTION
Wrong or over tightened torque	Replace with proper spring or refer
	to Installation section for proper
	spring height
Excessive air gap	Reset, refer to Installation Section 4

EXCESSIVE WEAR / OVERHEATING

AIR GAP CAUSE	AIR GAP CORRECTION
Low solenoid air gap	Reset air gap (refer to Air Gap
	Adjustment)
Disc pack dragging	Inspect endplate, hub and discs for
	dirt, burrs, wiring and other sources
	of interference preventing disc “float”
CYCLE RATE CAUSE	CYCLE RATE CORRECTION
Brake “jogging” exceeding coil	Reduce cycle rate or consider
cycle rate	alternate control method
Thermal capacity is being	Reduce cycle rate, use alternate
	control method or increase brake
exceeded
	size
ALIGNMENT CAUSE	ALIGNMENT CORRECTION
Broke endplate not concentric to	Motor register must be within
motor C-Face	.004” on concentricity.
Motor shaft runout is excessive	Must be within .002”; runout;
	consult motor manufacturer
Brake is being operated on a	Vertical separator springs must be
incline greater than 15° above or	used to prevent discs from
below horizontal	becoming cocked
WORN PARTS CAUSE	WORN PARTS CORRECTION
Friction disc excessively worn	Replace friction discs.
(disc can wear to 1/2 original
thickness or .093”)
Endplate, stationary disc or	Replace warped or worn component
pressure plate warped
Linkages and/or pivot pins worn	Replace all worn components
Motor shaft endfloat excessive	Endfloat must not exceed .020”;
	consult motor manufacturer
HUB CAUSE	HUB CORRECTION
Burr on hub interfering with disc	File off burr
“float”
Set screw backed out and	Retighten set screw; use Loctite®
interfering with disc	242 to help secure
MISCELLANEOUS	MISCELLANEOUS
Solenoid plunger not pulling	Check line voltage (±10% of
completely	nameplate rating) or replace worn
	solenoid assembly
Wiring is restricting disc pack	Reroute wiring
movement
Excessive stop time	Increase brake size/torque or use
(2 seconds or greater)	alternate control method
High Ambient temperature	Reduce cycle rate or use alternate
(in excess of 110°F)	method of cooling

Rexnord Industries, LLC., Stearns Division, 5150 S. International Dr., Cudahy, WI 53110, (414) 272-1100 Fax: (414) 277-4364 www.rexnord.com