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Designation
Axial Angular Contact Ball Bearing
Version 1
double-row
Body material
steel
Component material
nitrile rubber
Body surface finish
ground
B=Width
28 -0,25
D1=Outside diameter
57-0,01
D=Internal diameter
25-0,005
KZZ.=Abbreviation
2557-2RS
T1=Dynamic load ratings N
27500
T2=Static load ratings N
55000
U=Speed limit rpm
2600
Axial rigidity n/µm
750
Axial runout µm
2,0
Bearing friction torque Nm
0,40
Bore deviation µm
0-5
D2
40
Moment of inertia KGxcm²
0,486
Outside diameter deviation µm
0-10
R min.
0,3
R1 min.
0,6
Radial bearing clearance
pre-tensioned
Tightening torque prec. locknu
25
Tilt rigidity Nm/mrad
200
Width deviation µm
0-250
α
60°

Description

Material
Steel housing.
Nitrile rubber seal.
Version
Ground edges.
Note
Preloaded high-accuracy bearings with a 60° thrust angle. The bearings accept both radial and axial forces from both directions. Due to their preload, the angular contact ball bearings provide a high level of stiffness, excellent concentricity, precise tool positioning and repeatability.

The integrated low-friction seal effectively keeps dirt away from the bearing, thereby ensuring excellent operating safety and a long service life.

The bearing friction coefficient Mrl is a reference value.

The moment of inertia corresponds to that of the rotating inner ring.

The limiting speeds are applicable after grease is applied.
Technical Data
All bearings are supplied ready for mounting with lubricating grease type KE2P-35 acc. to DIN 51825.

Housing and shaft tolerances correspond to roundness tolerance class IT2 and perpendicularity tolerance class IT4.
Application
For thread drive bearing.
Temperature range
-30 °C to +120 °C.
Assembly
Precision slotted nuts must be used for mounting the threaded spindles.

To compensate for any material settling during assembly, tighten the slotted nuts using 2x tightening torque, loosen slightly and then tighten using the prescribed tightening torque.
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