Schaeffler YRTC User manual

High Precision Bearings for Combined Loads
Fitting and maintenance manual

Schaeffler Technologies MON 100 1
Page
High precision bearings for combined loads
About the mounting manual Symbols ................................................................................... 2
General safety guidelines Usage for the intended purpose ................................................ 2
Qualified personnel .................................................................. 2
Safety guidelines ...................................................................... 3
Preparations for fitting Bearings with magneto-resistive angular measuring system....... 5
Bearings with inductive angular measuring system.................... 7
Delivered condition of the bearings ........................................... 8
Initial greasing.......................................................................... 8
Bearing storage and storage life ................................................ 8
Compatibility and miscibility with anti-corrosion agents ............ 9
Cleaning of bearings ................................................................. 9
Removing bearings from packaging ........................................... 10
Transport of bearings ................................................................ 10
Design of fitting area................................................................. 12
Protection measures during fitting............................................. 13
Preparation of the adjacent construction ................................... 13
Selection of fasteners ............................................................... 14
Checking the tolerances of the screw mounting surfaces ........... 14
Fitting Checking the dimensional and
running accuracy of the bearings............................................... 15
Locating the bearing rings......................................................... 15
Function and safety checks Checking the bearing frictional torque ....................................... 19
Checking running accuracy........................................................ 19
Checking the fixing screws ........................................................ 20
Lubrication ................................................................................................ 21
Relubrication of bearings .......................................................... 22
Overlubrication......................................................................... 25
Initial operation ........................................................................ 25
Further information Publication requests ................................................................. 26

2 MON 100 Schaeffler Technologies
High precision bearings for combined loads
About the mounting manual This manual describes the fitting and maintenance of:
■ axial/radial bearings YRTC and YRTS
■ axial angular contact ball bearings ZKLDF
■ axial/radial bearings with integrated measurement ring YRTCM,
YRTSM, YRTCMA, YRTSMA and YRTCMI
Symbols The warning and hazard symbols are defined in accordance with
ANSI Z535.6-2011.
WARNING
In case of non-compliance, death or serious injury may occur. 
NOTICE
In case of non-compliance, damage or malfunctions in the product or
the adjacent construction may occur.

General safety guidelines Schaeffler accepts no liability for loss or damage arising from:
■ incorrect fitting
■ incorrect or inadequate maintenance
■ incorrect communication of the content to third parties or
a failure to do so
The content of this fitting and maintenance manual must be
communicated to the end user.
Usage for
the intended purpose
Axial/radial bearings YRT, YRTC and YRTS and axial angular contact
ball bearings ZKLDF are envisaged for use in chip-forming machine
tools and in particular for the bearing arrangements of high precision
rotary axes in milling and turning machines.
The bearings are intended for applications which require clearance-
free, precise and rigid axial/radial bearings or axial angular contact
ball bearings.
Axial/radial bearings YRTCM, YRTSM, YRTCMA, YRTSMA and YRTCMI,
which have an integrated measurement ring, are intended for
use in electrically driven, position-controlled machine tool axes.
Any usage outside the specified area or for purposes other than that
intended is at the personal responsibility of the user.
Qualified personnel The rotary table bearing may only be handled and mounted by
appropriately qualified personnel.

Schaeffler Technologies MON 100 3
Safety guidelines Ensure correct handling during the individual phases:
■ opening the packaging
■ transporting the bearing
■ mounting the bearing
■ screw mounting the bearing rings
Transport and storage Protect bearings from exposure to load resulting from incorrect
transport or storage. Large bearings should only be stored lying flat
and should be transported lying flat if possible.
Unpacking, transport, packing and storage may only be performed by
appropriately qualified personnel.
Mounting Before and during fitting, the bearings and measuring system
must be handled with care and in accordance with this fitting and
maintenance manual.
Bearings should only be fitted using the tools and fitting aids
specified. If unsuitable or contaminated tools and fitting aids are
used, this will seriously impair the function of the bearings and
significantly reduce their operating life.
Mounting, regreasing, the grease distribution cycle and
commissioning may only be performed by appropriately qualified
personnel.
Adjacent construction The sequence of operations depends on the design of the adjacent
construction. It is therefore not possible to provide a single descrip-
tion that includes all the fitting variants.
Since, in the majority of applications, the bearing inner ring is fitted
on the shaft first and the bearing outer ring is then fixed in place,
the fitting of the bearings is described on the basis of this fitting
process.
If the adjacent construction is different, fit the bearing appropriately
or contact us for advice.

4 MON 100 Schaeffler Technologies
High precision bearings for combined loads
Measurement ring Protect the measurement rings against shock loads.
During unpackaging and restorage, ensure that the measurement
ring does not come into contact with tools, wrapping loops or
eye bolts.
Similarly, ensure that the cylinder head screws, tools and screw
assembly tools do not come into contact with the measurement ring
during mounting and screw mounting.
Measurement rings can be scratched, deformed or destroyed in
contact with tools, objects, eye bolts or wrapping loops and under
exposure to high forces. In particular, damage to or deformation
of the measurement ring and its structure will impair or destroy
the angular measurement accuracy.
Measurement ring and
protective strip
(YRTCM, YRTSM)
Shock loads can lead to flaking of the composite material of
the measurement ring.
The protective strip is a piece of adhesive tape and is used to provide
protection during transportation. It must be removed prior to initial
operation.
Measurement ring and
cover ring
(YRTCMA, YRTSMA and YRTCMI)
Shock loads can damage the lattice structure of the measurement
ring and lead to measurement errors.
The cover ring is manufactured from stainless steel and must not be
removed, but must remain on the inner ring.

Schaeffler Technologies MON 100 5
Preparations for fitting Axial/radial bearings and axial angular contact ball bearings are
precision machine elements. These high precision rolling bearings
will only achieve their maximum operating life and functional
capability if they are fitted correctly.
Bearings with
magneto-resistive angular
measuring system
Axial/radial bearings YRTCM and YRTSM correspond in mechanical
terms to series YRTC and YRTS, but are additionally fitted with
a magnetically coded measurement ring and a protective strip.
Measurement rings are manufactured from a composite material that
has a magnetic multipolar arrangement. This is scanned by magneto-
resistive means.
The protective strip is a piece of adhesive tape and is used to provide
protection during transportation. It must be removed prior to initial
operation.
The measurement ring, which is protected by a protective strip
during transportation and mounting, is located on the cylindrical
outside surface of axial/radial bearings YRTCM and YRTSM.
The measurement ring must be protected against shock loads.
During unpackaging and restorage, ensure that the measurement
ring does not come into contact with tools, wrapping loops or
eye bolts. Similarly, ensure that the cylinder head screws, screw
assembly tools and other tools used do not come into contact with
the measurement ring during mounting and screw mounting of
the outer ring.

6 MON 100 Schaeffler Technologies
High precision bearings for combined loads
NOTICE
External magnetic fields damage the magnetic measurement ring.
Keep the measurement ring away from magnetic sources, to avoid
partial mismeasurements by the system. A field strength of approxi-
mately 70 mT or higher immediately on the coding carries the risk
of damage to the magnetic poles of the measurement ring.
Magnetic dial gauge stands must not be placed directly on the coded
washer (guide value: at least 100 mm distance in air or 10 mm
unalloyed steel).

 Minimum distance ⬎ 100 mm
Figure 1
Minimum distance between
magnetic measurement stand and
magnetic measurement ring
0000C04C0000C04C
 Shielding ⬎ 10 mm
Figure 2
Shielding by unalloyed steel
0000C04E0000C04E

Schaeffler Technologies MON 100 7
Bearings with
inductive angular measuring
system
Axial/radial bearings YRTCMA, YRTSMA and YRTCMI correspond in
mechanical terms to series YRTC and YRTS, but are additionally fitted
with a measurement ring, which can be scanned by inductive means,
and a cover ring.
The measurement ring and the cover ring, which are components of
the angular measuring system, are located on the cylindrical outside
surface of axial/radial bearings YRTCMA, YRTSMA and YRTSMI.
Measurement rings are manufactured from stainless steel and have
a high-precision lattice structure, which is scanned by inductive
means. The cover ring is manufactured from stainless steel and must
not be removed, but must remain on the inner ring.
Damage to the measurement ring and cover ring, which can be
caused by contact with tools, objects, eye bolts or wrapping loops
and exposure to high forces, will impair measuring accuracy and
result in the functional failure of the measuring system.
When fitting and screw mounting the outer ring, ensure that
the cover ring does not come into contact with cylinder head screws,
screw assembly tools and other tools.
Guide the axial/radial bearing with angular measuring system cen-
trally into the axle housing, to ensure that the axial/radial bearing
and, in particular, the measurement ring, do not come into contact
with sharp edges or metal burr.
Figure 3
Axial/radial bearing with
inductive angular measuring
system
0019362100193621

8 MON 100 Schaeffler Technologies
High precision bearings for combined loads
Delivered condition of
the bearings
The bearings are wrapped in anti-corrosion paper and individually
packed in film. Smaller sizes are also supplied in multiple packs.
Initial greasing The bearings are greased:
■ YRTS, YRTSM and YRTSMA with
a lubricating grease according to Arcanol L
OAD 150
■ YRTC, YRTCM, YRTCMA, YRTCMI and ZKLDF with
a lubricating grease according to Arcanol M
ULTITOP
The rotational resistance is heavily dependent on the greasing of
the bearing. The frictional torque values given in
the dimension tables (Catalogue HR 1, Rolling Bearings, and
TPI 120, High Precision Bearings for Combined Loads)
are only valid for bearings with the original greasing.
Miscibility of greases Greases may be mixed if the following preconditions are fulfilled:
■ same base oil
■ compatible thickener type
■ similar base oil viscosities
(differing by no more than one ISO viscosity grade VG)
■ matching consistency
(NLGI consistency class)
If there is any doubt, please consult the lubricant manufacturer.
Bearing storage and
storage life
The shelf life of the bearings is limited by the storage life of
the grease.
Experience shows that the greases used, with a mineral oil base,
can be stored for up to 3 years under the following conditions:
■ closed room
■ dry, clean rooms with temperatures between 0 °C and +40 °C
■ relative humidity up to a maximum of 65%
■ no influence of chemical agents
(vapours, gases, fluids)
After long storage periods, the frictional torque may temporarily
be higher than that of freshly greased bearings. The lubricity of
the grease may also have deteriorated.