Stearns Series 321, Series 322 Catalog Page
Series 321 & Series 322
Armature Actuated Brakes
Shown: Size 2.8 with
thru-shaft & manual
release options
Shown: Size 1.8 flange
mount with manual
release option
Size 1.2 and 1.8
Totally Enclosed Non-Ventilated (TENV)
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Direct-Acting Brake - Quiet Operation
• Torque Rating: 3 lb-in through 72 lb-in
• Enclosure Rating: 321 Series IP42 322 Series IP54
• UR and CUR recognized insulation system - File E-125303;
and sizes 1.8 & 2.8 brakes and 48C & 56C motor frame brakes with
internal power supply File E-71115
• Class B temperature rise with Class H mag wire
• Pressure plate mount
• Installation and Service Instructions: P/N 8-078-901-00
• Optional:
Optional “double D” friction discs are available in
3-7 lb-in dynamic and 3-15 lb-in holding brakes. DD shafts fit the brake
directly without a brake hub, no shaft keyway cost and simplify assembly
• Optional: Maintained manual release lever, or non-maintained
pull release
• Optional: Through-shaft
• Optional: AC Rectifiers - Internal, or external in-line (availability
depends on size)
Size 2.8
Manual
release
option
Manual
release
option
Dimensions in Inches (millimeters)
Size
1.2 Dynamic 3 .34
1.2 Holding 5 .56
1.8 Dynamic 7 .79
1.8 Holding 15 1.69
1.8 Dynamic 15 1.69
2.8 Dynamic 35 3.95
2.8 Dynamic 50 5.65
2.8 Holding 72 8.14
Nominal Static Torque
Lb-in Nm Series Mag Body Ø
Basic Model
Number
3-21-24
3-22-24 322 1.875 (47.625) .05 (1.27)
3-21-25
3-22-25 322 1.875 (47.625) .05 (1.27)
3-21-44
3-22-44 322 .05 (1.27)
3-21-45 321 .02 (.51)
3-22-45 322 .05 (1.27)
3-21-46 321 .02 (.51)
3-22-46 322 .05 (1.27)
3-21-74
3-22-74 322 .125 (3.18)
3-21-75
3-22-75 322 .125 (3.18)
3-21-77
3-22-77 322 .125 (3.18)
AH
.904
(22.962)
1.080
(27.432)
1.296
(32.918)
_ _
_ _
_ _
.12
(3.05)
.12
(3.05)
321 1.77 (44.96) .02 (.51)
321 1.77 (44.96) .02 (.51)
321
2.50 (63.50)
321
321
321
Specifications
7
Hub and
Disc inertia
(Oz-in-sec
7.02 x 10
4.8 x 10
2.3 x 10
2
-3
-4
-3
-3
-3
Thermal Capacity
)
**Set screws located 120° from keyway
Size
1.2 Dynamic 3-2X-24 3 (.34)
1.2 Holding 3-2X-25 5 (.56)9
1.8 Dynamic 3-2X-44 7 (.79)
1.8 Dynamic 3-2X-46 15 (1.69)
2.8 Dynamic 3-2X-74 35 (3.95) 2.0 .91 17
2.8 Dynamic 3-2X-75 50 (5.65) 2.0 .91 17 2.3 x 10
2.8 Holding 3-2X-77 72 (8.14) 2.0 .91 22 2.3 x 10
Basic
Model
Number
Nominal
Static Torque
Lb-in (Nm)
Approx. Weight
lbs kg in mm
.4 .18
1.3 .59 10
Power
(watts)
D
3.66 (92.96)
3.66 (92.96)
3.66 (92.96)
HP-sec/min
Consult Factory 3/8 9
.26 1/2** 12**1.8 Holding 3-2X-45 15 (1.69)
.17
Hub
Location
.02 (.51)
.100 (2.54)
.100 (2.54)
.100 (2.54)
Maximum
Bore Size
1/2 12
1/2 12
1/2 12
Hub
Length
.19
(4.83)
.25
(6.35)
.25
(6.35)
.25
(6.35)
.25
(6.35)
73
Series 321 & Series 322 Continued
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SIZE 1.2
Inside Mount
SIZE 1.8 Inside Mount
Brake
released
SIZE 1.2
Flange Mount
321 Series only
SIZE 1.8 Flange Mount
Brake
released
74
NEW
72 mm
bolt circle
SIZE 2.8
Inside Mount
SIZE 2.8
72mm Mount
*Also, the location of the external leads for the 322 series is on the backside of the magnet body - not on the
side (as shown in the above drawings) as with the 321 series.
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