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NTN QJ311 four-point contact ball bearing with a 55 mm straight bore. Open design accommodates combined radial and axial loads in both directions. Suitable for gearboxes, pumps, and industrial machinery requiring axial load capacity.
MODEL QJ311
$412.74 Each
Prices are subject to change
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Returnable:No
a (in)
1.9882
B (in)
1.1417
Ball Material
Steel
Ball material
Steel
Bore Type
Round
Bore type
Round
Cage Material
Brass
Cage material
Brass
Cage Type
High Strength, 2 piece, Machined
Cage type
High strength, 2 piece, machined
Configuration
One
Contact Angle
30 °
Contact angle
30 º
d (in)
2.1654
D (in)
4.7244
Da max
4.3307 in
da min
2.5591 in
Dynamic Load Rating
23800 lbf
Dynamic load rating
23800 lbf
Enclosure
Open
I.D.
55 mm
Limiting Speed - Grease
4600 RPM
Limiting speed - grease
4600 RPM
Limiting Speed - Oil
6100 RPM
Limiting speed - oil
6100 RPM
Material
High carbon chrome steel
O.D.
120 mm
Operating Temperature Range
-40 to 250 °F
Operating temperature range
-40 to 250 ºF
Precision
Class 0
r (in)
0.0787
Radial Internal Clearance
CN
Radial internal clearance
CN
ras max
0.0787 in
Static Load Rating
38000 lbf
Static load rating
38000 lbf
Type
Four-Point Contact Ball Bearing
Technical Specifications
| Type | Four-Point Contact Ball Bearing |
|---|---|
| Bore Type | Round |
| Material | High Carbon Chrome Steel |
| Cage Type | High Strength, 2 piece, Machined |
| Cage Material | Brass |
| Ball Material | Steel |
| Limiting Speed - Oil | 6100 RPM |
| Limiting Speed - Grease | 4600 RPM |
| Precision | Class 0 |
| Configuration | One |
| Contact Angle | 30 |
| Radial Internal Clearance | CN |
| Static Load Rating | 38000 lbf170000 N170.00 kN |
| Dynamic Load Rating | 23800 lbf106000 N106.00 kN |
| Enclosure | Open |
| Operating Temperature Range | -40 to 250 F-40 to 120 C |
Dimensional Specifications
| |
| d | 2.1654 in55.000 mm |
|---|---|
| D | 4.7244 in120.000 mm |
| B | 1.1417 in29.000 mm |
| r | 0.0787 in2.000 mm |
| a | 1.9882 in50.500 mm |
| da min | 2.5591 in65.000 mm |
| Da max | 4.3307 in110.000 mm |
| ras max | 0.0787 in2.000 mm |
How do I choose the right type of bearing for my application?
Start with the load and how it’s applied. You need to know if you’re dealing with radial loads, axial loads, or a mix of both. Then look at speed, operating environment, and space constraints. For example, ball bearings are great for high speed and lighter loads, while roller bearings handle heavier loads but usually at lower speeds. If there’s contamination, moisture, or heat involved, you may need sealed bearings or specific materials. In most cases, the right choice comes down to matching load type, speed, and environment to the bearing design.
What is the difference between deep groove and angular contact ball bearings?
Deep groove ball bearings are the most common type. They’re designed to handle mainly radial loads, but they can also take some axial load in both directions. They’re simple, versatile, and used in everything from motors to conveyors. Angular contact ball bearings are built for combined loads, especially where there’s significant axial force in one direction. They’re often used in pairs and are common in higher precision or higher load applications like pumps and gearboxes. If your load is mostly radial, go deep groove. If axial load matters more, angular contact is usually the better choice.
| Brand | Boston Gear |
| Model | SSHF7210B-30KC-B5-HS1-P19 |
