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SKF
Four Point Contact B. SKF QJ211 MA
- Technical data
- Inner diameter
- 55 mm
- Outer diameter
- 100 mm
- Width
- 21 mm
- Seal
- None, open bearing
- Cage
- Brass cage
- Clearance
- Normal radial clearance
- Running accuracy
- Dimensional accuracy P6, Running accuracy P5
- Groove(s) on outer ring
- Without groove
- Design
- Split inner ring
- Temperature range
- -30 to +150 °C
- Version
- Explorer
- Weight
- 0,758 kg
| Scale quantity | Your discount | Unit price |
|---|---|---|
| 10 | 6,19 € | 117,68 € |
| 20 | 12,39 € | 111,48 € |
Four Point Contact B. SKF QJ211 MA
The SKF QJ211 MA four-point bearing, with dimensions of 55 × 100 × 21 mm, accommodates axial forces in both directions whilst maintaining a narrow bearing width.
The QJ211 MA four-point bearing is a single-row angular contact ball bearing with a split inner ring, which accommodates axial loads in both directions. SKF manufactures this version in the Explorer class with a bore of 55 mm, an outside diameter of 100 mm and a width of 21 mm. Due to the geometry of the raceways, this component requires less axial installation space than two separate angular contact ball bearings. Design engineers primarily use the open bearing where a defined axial shaft guidance is required in a slim design.
What is the QJ211 MA four-point bearing suitable for?
This rolling bearing is suitable for mountings subject to predominantly or purely axial loads in alternating directions. It is frequently used in multi-part shaft mountings as a pure axial bearing, with the outer ring mounted radially free in the housing. In such arrangements, a separate radial bearing absorbs the radial forces. The QJ211 MA four-point bearing withstands operating temperatures ranging from -30 to +150 degrees Celsius and is suitable for drives operating under demanding thermal conditions.
What are the advantages of the split inner ring and the brass cage?
The two-piece inner ring allows a large number of balls to be fitted and simplifies the assembly and disassembly of the shaft connection. The guided brass cage (suffix MA) is characterised by high strength and guides the rolling elements accurately even during rapid changes in speed. SKF manufactures this model to a higher standard of precision: dimensional accuracy complies with tolerance class P6, whilst running accuracy is to class P5. This combination contributes to low-vibration operation.
What are the dimensions of the QJ211 MA four-point bearing?
The bearing has an internal diameter of 55 mm, an external diameter of 100 mm and a width of 21 mm. It is an open bearing without integrated sealing washers. When designing the mounting dimensions, the mating surfaces in the housing and on the shaft should be machined to a precise fit in order to utilise the full load-carrying capacity.
Why does this four-point bearing have a split inner ring?
The two-piece inner ring allows the outer ring, together with the ball race, to be fitted separately from the inner ring halves. This non-self-retaining design facilitates installation onto the shaft. Furthermore, the design allows for a higher packing density of rolling elements, enabling the bearing to accommodate high axial forces in both directions whilst maintaining a narrow overall axial width.
What do the tolerance classes P6 and P5 mean for the QJ211 MA?
These specifications define tighter tolerance levels than the standard tolerance. Dimensional accuracy in Class P6 limits deviations in bore and outside diameters to lower values. The running accuracy specified in P5 describes particularly precise concentricity of the rings. Together, these two characteristics reduce vibrations in the system and are suitable for precisely guided shafts.
What is the temperature range for which the bearing is designed?
The permissible operating temperature range is between -30 and +150 degrees Celsius. This range is limited by the dimensional stability of the bearing rings and the brass cage. As the bearing is operated in an open configuration, the chosen external lubricant determines the actual thermal operating limit in practical application.
What type of lubrication does the QJ211 MA open four-point bearing require?
As an open roller bearing, this design has no factory-fitted grease and no sealing elements. During operation, it is supplied with lubricating oil or grease via the surrounding structure. An external seal on the housing serves to prevent the ingress of dirt particles or moisture and to retain the lubricant within the bearing housing.
What is the difference between a four-point bearing and a standard deep-groove ball bearing?
A deep-groove ball bearing primarily accommodates radial loads and only moderate axial forces. The QJ211 MA four-point contact bearing, on the other hand, is specifically designed for high axial loads in both directions. Its pointed-arc raceways result in four-point contact, enabling the bearing to replace two separate angular contact ball bearings in a space-saving design.
SKF Group
Sven Wingquists Gata 2, 415 50 Gothenburg, Sweden
info@skf.com, https://www.skf.com/uk/footer/site-ownership
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