FAG234436MSPDouble Direction Axial Angular Contact Ball Bearing 180 x 280 x 120 mm, 60° Contact Angle, Two Opposed Ball Rows, Solid Brass Cages, Special Precision — Ball Screw and Spindle Thrust Bearing

Product Description

What this part is

A double direction axial angular contact ball bearing — 180 mm bore, 280 mm outside diameter, 120 mm overall height. This is not an ordinary angular contact bearing and it is not a plain thrust bearing. It is the precision component machine tool builders put behind a heavily loaded ball screw or a vertical spindle: two rows of balls running at a steep 60° contact angle, arranged back to back inside one unit so that axial load is carried in both directions with very high stiffness and almost no axial play.

Decoding the designation

2344 — FAG’s double direction axial angular contact ball bearing series for main spindles and screw drives.
36 — bore code, 36 x 5 = 180 mm.
M — machined solid brass cages.
SP — special precision, FAG’s restricted-tolerance grade for this range.

The unit is separable and is supplied as a set of matched components: two solid shaft locating washers, a spacer ring between them, a housing locating washer, and the two ball and cage assemblies.

What these specs mean in practice

The 60° contact angle is what defines this bearing. At 60° the load line runs much closer to the bearing axis than in an ordinary 15° or 25° spindle bearing, so almost all of the capacity is axial: a dynamic axial rating of 235 kN and a static axial rating of 840 kN in a bearing only 280 mm across. Axial stiffness is correspondingly high, which is the entire reason for specifying it — on a ball screw axis, positioning accuracy under cutting load is set by the axial deflection of the screw support, and a soft support turns into lost accuracy and chatter no matter how good the screw and the encoder are. What you give up is speed and radial capacity: this bearing is not intended to carry meaningful radial load, and its limiting speed is 3000 rpm.

Because the two rows oppose each other inside one unit, the bearing handles thrust reversals without any need to set it against a second bearing elsewhere on the shaft. That is what makes it practical on a screw drive, where the load reverses every time the axis changes direction, and where any backlash in the support shows up directly as lost motion.

The solid machined brass cages are the heavy-duty choice. Brass holds its geometry under high load, tolerates elevated temperature and marginal lubrication better than a polymer cage, and does not fatigue the way a pressed cage would under the repeated thrust reversals this bearing is built for.

Published ratings and mounting data

Bore: 180 mm
Outside diameter: 280 mm
Overall height: 120 mm
Contact angle: 60°
Rows of balls: 2, opposed (double direction)
Dynamic axial load rating: 235 kN
Static axial load rating: 840 kN
Fatigue load limit: 49.5 kN
Limiting speed: 3000 rpm
Operating temperature range: −30 °C to +150 °C
Approximate mass: 20.5 kg

Quantity and configuration

One complete bearing unit. Because it is separable, the components arrive as a matched set — two shaft locating washers, the spacer ring, the housing locating washer and both ball and cage assemblies. Keep them together and keep them in their original relative orientation; the washers and spacer are ground as a set and mixing components between units destroys the preload and the axial accuracy.

Fitting notes

The axial accuracy of this bearing is only as good as the faces it sits against. Both abutment faces — the shaft shoulder and the housing face — need to be ground square to the axis, because any out-of-square face tips the washers and loads one row harder than the other. Clamp firmly and evenly; this bearing is designed to be axially clamped, not floated. At 20.5 kg and 180 mm bore, plan the handling before you start, keep the components in order as you separate them, and protect the ground washer faces from knocks. Lubricate with a grease or oil suited to a heavily loaded, comparatively slow-turning thrust position rather than a high-speed spindle grease, and do not overfill.

Interchange guidance

The 2344 series is FAG’s own, and the number is used across the industry as the reference for this envelope. Comparable double direction axial angular contact bearings for screw drives include INA/Schaeffler ZKLDF and ZKLN ranges in smaller sizes, NSK TAC series, NTN BST series and RHP BSB series — all built for the same job at a steep contact angle, though sizes and mounting details differ. Within FAG, 234436-BM1-SP and 234436-M-SP-2Z are execution variants of the same envelope. When cross-referencing, the contact angle and the overall height are the two dimensions that must match; a 60° screw support bearing and an ordinary 25° angular contact bearing of similar bore are not interchangeable in either direction.