QJ1248-MPA | Four-point contact ball bearings|

Specifications of FAG Bearing QJ1248-MPA

Dimensions

α	45 °	Contact-angle
a	680 mm	Distance between the apexes of the pressure cones
d1	314.95 mm	Shoulder diameter inner ring
D1	367.9 mm	Shoulder diameter outer ring
rmin	4 mm	Minimum chamfer dimension

Main Dimensions & Performance Data

Cr	660000 N	Basic dynamic load rating, radial
C0r	1220000 N	Basic static load rating, radial
d	240 mm	Bore diameter
Cur	38000 N	Fatigue load limit, radial
nG	2600 1/min	Limiting speed
D	440 mm	Outside diameter
nδr	1390 1/min	Reference speed
B	85 mm	Width

Mounting dimensions

Da max	423 mm	Maximum diameter of housing shoulder
ra max	3 mm	Maximum recess radius
da min	257 mm	Minimum diameter shaft shoulder

Temperature range

Tmax	200 ℃	Operating temperature max.
Tmin	-30 ℃	Operating temperature min.

Product description of FAG Bearing QJ1248-MPA

FAG Bearing QJ1248-MPA , Four-point contact ball bearings are angular contact ball bearings with raceways that are designed to support axial loads in both directions. They need considerably less space than double-row bearings.,Four-point contact bearings are single-row angular contact ball bearings and therefore require significantly less space in an axial direction than double-row designs.

The bearings comprise solid outer rings, split inner rings and ball and cage assemblies with brass or poly-amide cages. The two-piece inner rings enable a large complement of balls to be accommodated. The inner ring halves are matched to the particular bearing and must not be interchanged with those of other bearings of the same size. The outer ring with the ball and cage assembly can be mounted separately from the two inner ring halves.

FAG Bearing QJ1248-MPA, Four point contact bearings are similar in their structure to double row angular contact ball bearings, but are considerably narrower in an axial direction due to only one raceway groove. Since the centre of curvature of the arc-shaped raceways on the inner ring and outer ring are offset relative to each other, the balls are in contact with the bearing rings at four points under radial load. For this reason, four point contact bearings are only used under predominantly axial load.

Due to the large contact angle on both sides, the bearings can support alternating, pure axial or predominantly axial loads.

If predominantly radial load is present, four point contact bearings should not be used due to the higher friction in the four point contact.

One of the two bearing rings, normally the inner ring, is split for assembly reasons in order to allow filling with the balls. As four point contact bearings FAG Bearing QJ1248-MPA are often fitted without radial retention, the outer rings can be designed as an option with retaining slots to prevent rotation.

A main area of application is in gearbox engineering, where axial loads are present in both directions and close axial guidance is required in conjunction with a small bearing width.

Four point contact bearings are often combined with a radial bearing and used as an axial bearing with radial clearance in a housing.

FAG Bearing QJ1248-MPA, Four point contact bearings are particularly suitable where: • Predominantly axial loads must be supported • The axial design envelope is not sufficient for double row radial angular contact ball bearings • Radial forces must be supported by a separate radial bearing • Axial forces occur in both directions and a close axial clearance is required in conjunction with a small bearing width, e. g. in gearbox engineering