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SKF
Four Point Contact B. SKF QJ224 N2MA
- Technical data
- Inner diameter
- 120 mm
- Outer diameter
- 215 mm
- Width
- 40 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
- 2 retaining grooves on outer ring shifted by 180 degrees
- Design
- Split inner ring
- Temperature range
- -30 to +150 °C
- Version
- Explorer
- Weight
- 6,7 kg
| Scale quantity | Your discount | Unit price |
|---|---|---|
| 2 | 36,33 € | 690,25 € |
| 3 | 72,65 € | 653,93 € |
Four Point Contact B. SKF QJ224 N2MA
SKF QJ224 N2MA four-point bearing: 120x215x40 mm, with a split inner ring, brass cage and retaining grooves for accommodating axial loads in both directions in mechanical engineering.
The SKF QJ224 N2MA four-point bearing is a single-row radial ball bearing which, thanks to its special raceway geometry, can accommodate high axial forces in both directions. With key dimensions of a 120 mm bore, 215 mm outside diameter and 40 mm width, this rolling bearing requires less axial installation space than comparable double-row angular contact ball bearings. The SKF Explorer version is characterised by dimensional accuracy to P6 and running accuracy to P5. As an open bearing with a brass cage, it is designed for operating temperatures ranging from -30 to +150 degrees.
What is the QJ224 N2MA four-point bearing suitable for?
The QJ224 N2MA four-point bearing is particularly suitable for applications where alternating or purely axial loads need to be accommodated within limited axial installation space. This design is frequently used in gearboxes or as a purely axial bearing in combination with a separate radial bearing. Thanks to the split inner ring, the design accommodates a large number of rolling elements, which enhances the axial load-carrying capacity. Where the bearing is used purely for axial support, a radial housing clearance for the outer ring is recommended.
What is the function of the split inner ring and retaining grooves?
The split inner ring allows the outer ring and the inner ring halves to be assembled separately, which makes installation on the shaft considerably easier. Two retaining grooves in the outer ring, offset by 180 degrees, prevent the bearing from rotating within the housing when suitable retaining pins are engaged. As this is an open bearing without an integrated seal, external sealing of the bearing housing against dirt and lubricant loss is required. Care must be taken to ensure proper lubrication within the temperature range of -30 to +150 degrees.
What are the dimensions of the QJ224 N2MA four-point bearing?
The bearing has an internal diameter of 120 mm, an external diameter of 215 mm and a width of 40 mm. These standardised dimensions allow for a direct replacement during maintenance work or new designs. The brass cage ensures stable guidance of the balls.
Why does the bearing have two retaining grooves on the outer ring?
The two retaining grooves on the outer ring, offset by 180 degrees, provide a positive anti-rotation lock within the bearing housing. In combination with suitable retaining pins, they prevent the outer ring from rotating unintentionally under dynamic axial forces or when there is play in the bearing seat.
How does the split inner ring affect assembly?
A split inner ring means that the four-point bearing is a non-self-retaining assembly. This allows the outer ring, together with the ball cage, and the two halves of the inner ring to be fitted separately. This simplifies installation in confined spaces and also allows for the inclusion of more rolling elements to accommodate high axial loads.
What do the tolerance classes P6 and P5 mean for this bearing?
These specifications indicate higher levels of accuracy compared with standard tolerances. Dimensional accuracy P6 defines tighter manufacturing tolerances for mating dimensions such as bores and external diameters. P5 running accuracy ensures precise concentricity with minimised radial and axial runout during operation in demanding industrial applications.
Does the open bearing require separate lubrication and sealing?
As an open roller bearing, this version does not feature any factory-fitted sealing washers. You must therefore seal the bearing housing externally against dirt and moisture via the housing design. In addition, a suitable grease or oil lubricant must be applied for the intended operating range between -30 and +150 degrees.
What is the clearance in the four-point bearing?
This product is manufactured with standard radial bearing clearance. This standard bearing clearance is suitable for normal operating temperatures and typical fit conditions on the shaft and housing. It helps to ensure that, once fitted, the bearing neither seizes nor exhibits excessive play at operating temperature.
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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