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.

Schaeffler Technologies MON 100 9
Compatibility and
miscibility with
anti-corrosion agents
The anti-corrosion agents in bearings with an oil-based preservative
are compatible and miscible with lubricating oils having a mineral
oil base. Compatibility must be checked if, for example, synthetic
lubricants are to be used.
If there is an incompatibility, wash out the anti-corrosion oil before
greasing. This is necessary in the following cases:
■ products based on alkoxyfluoroether
■ products based on polyglycol oil
■ use of silicone oils
■ change of lubricant
■ contamination of the bearings
If in doubt, please contact the relevant lubricant manufacturer.
Cleaning of bearings In general, it is not necessary to remove the anti-corrosion agents
from bearings coated with an oil-based preservative.
NOTICE
Risk of damage due to the introduction of contaminants.
Contaminants can impair the function and operating life of bearings.
Use a lint-free cloth to clean the external surfaces of the bearing only.
Check the contaminant content of the cleaning baths. A contaminant
content of 0,1% must not be exceeded. 
Cleaning can be carried out using:
■ organic cleaning agents
– paraffin oil free from water and acid,
petroleum ether (not petrol), freon 12 substitutes
■ thin, clean oil for hot cleaning
– oil with a flash point of at least +250 °C should be used and
heated to approx. +120 °C
– in addition to effective cleaning, this method also protects
the bearings temporarily against corrosion
Legal regulations on environmental protection and on health and
safety at work in the respective country of use must be observed,
in addition to application information provided by the manufacturer
of the product used.

10 MON 100 Schaeffler Technologies
High precision bearings for combined loads
Removing bearings from
packaging
The original packaging protects the bearing from minor transport
damage and contamination.
NOTICE
To prevent corrosion, ensure your hands are clean and dry.
Wear safety gloves.

 Bearings should only be removed from their original packaging
immediately before assembly.
 If the original packaging is damaged, the bearings must be
checked.
 Clean any contaminated bearings.
Multi-item packaging For multi-item packaging with dry preservation, the protective
vapour phase is only effective in closed packaging.
 The packaging should be closed again immediately.
 Ungreased bearings should be oiled or greased immediately.
Transport of bearings The bearing must be transported correctly.
WARNING
In order to prevent the occurrence of personal injury or damage,
the transport specifications must be observed.
Use suitable technical accessories to lift heavy components.
The mounting personnel must be familiar with correct usage of
the accessories and must observe all safety specifications relating to
the handling of suspended loads.
Only use lifting gear, tackle and cranes that are designed, tested and
approved for the specific intended purpose.
The presence or movement of persons, or body parts, under sus-
pended loads is not permitted.


Schaeffler Technologies MON 100 11
NOTICE
To prevent damage in transit, ensure correct transport. Do not
position the bearings vertically. Bearings must not be wrapped in
a chain. Bearings should never be supported at one point only for
lifting.

 Large bearings should only be stored lying flat and should be
transported lying flat if possible.
 Heavy bearings must only be transported using a hoist attached to
the eye bolts or by means of textile slings.
Figure 4
Storage lying flat
0000BE900000BE90
Figure 5
Transport using hoist and
eye bolts
0000BE6D0000BE6D

12 MON 100 Schaeffler Technologies
High precision bearings for combined loads
Design of fitting area  Ensure that work surfaces are bright, clean and free from fibres
and that lighting conditions are good.
 Rolling bearings should be fitted in the workshop if possible.
If this is not possible:
 Cover the machine.
 Protect the bearings against contamination from the surrounding
area.
 Bearings should only be unpacked immediately before fitting and
must be protected against contamination.
NOTICE
The fitting area must be kept clean and free from dust.
Contamination will impair the function and operating life of
the bearings.
To prevent corrosion, ensure your hands are clean and dry.
Wear safety gloves. The bearings must be protected against moisture
and aggressive media.

Figure 6
Design of fitting area
0000BE670000BE67

Schaeffler Technologies MON 100 13
Protection measures during
fitting
If fitting the bearings in complex fitting processes is very time-
consuming or fitting is interrupted, take appropriate measures to
protect bearings against contamination and damage.
The machine area can be completely covered using VCI paper or
plastic sheeting.
If this is not possible, cover the exposed bearing and shaft with
a clean, lint-free cloth.
Preparation of
the adjacent construction
The locating surfaces for the bearing rings must be clean and free
from burrs for fitting.
Cleaning
the adjacent construction
Suitable cleaning agents include petroleum, diesel oil and commer-
cially available grease solvents such as acetone or isopropanol.
Legal regulations on environmental protection and on health and
safety at work in the respective country of use must be observed,
in addition to application information provided by the manufacturer
of the product used.
 Smooth the locating surfaces and burrs using an oil stone.
 Apply cleaning agents to the locating and bearing seating
surfaces using a brush or suitable cloth.
 Clean and dry the surfaces.
NOTICE
Ensure that all adjacent components and lubrication holes are free
from cleaning agents, solvents, washing emulsions and detaching
particles. If the adjacent construction and lubrication holes are not
completely clean, the raceway system may become contaminated or
the fit surfaces may rust.


14 MON 100 Schaeffler Technologies
High precision bearings for combined loads
Selection of fasteners Bearings must only be fixed using the screw types specified.
It is essential that the information in the following sources is
followed:
■ technical proposal
■ Catalogue HR 1, Rolling Bearings, dimension tables
■ TPI 120, High Precision Bearings for Combined Loads
NOTICE
The specifications relating to the fasteners must be observed.
Any deviations will influence the effectiveness of the screw connec-
tion and the function, such as frictional torque and rigidity, as well
as the life of the bearings.
As fixing screws, use cylinder head screws of grade 10.9 to
DIN EN ISO 4762 only. For other grades, please contact Schaeffler.
The user should ensure a screw connection with the adjacent
construction and strength thereof to guideline VDI 2230.

Checking the tolerances of
the screw mounting surfaces
The dimensional, form and positional tolerances for the screw
mounting surfaces on the adjacent construction must be within
the stated values in accordance with TPI 120, High Precision
Bearings for Combined Loads, and Catalogue HR 1, Rolling Bearings.
The measurement method depends on the following factors:
■ the measuring equipment used
■ the geometry of the adjacent components
■ the requirements for running accuracy
In order to achieve the high measurement accuracy required,
a measuring machine should be used for the check if necessary.
The adjacent construction should be measured under the usual
technical conditions (temperature in the region of the reference
temperature +20 °C, no wide component temperature variations).
The components should be allowed sufficient time to reach these
temperatures where required, for example, in the event of transport
from a cold environment to the hall.
NOTICE
The screw mounting surfaces of the adjacent construction must not
exceed the permissible geometrical tolerances according to the
diagram, see TPI 120, High Precision Bearings for Combined Loads,
and Catalogue HR 1, Rolling Bearings.


Schaeffler Technologies MON 100 15
Fitting
Checking the dimensional and
running accuracy of
the bearings
 To check the dimensional tolerances D and d, loosen the retaining
screws used to secure the bearing during transport.
The data supplied for the bearing diameter in TPI 120, High Precision
Bearings for Combined Loads, and in Catalogue HR 1, Rolling
Bearings, are mean values.
The running accuracy of the bearings can only be measured on
a bearing that is already fitted, screw mounted and fully supported.
The full bearing running accuracy can only be transmitted to
the complete assembly if there is a clearance-free fit on the rotating
bearing ring.
Locating the bearing rings In order to facilitate fitting, the bearings can be heated.
Heating by between 10 K and 20 K is generally sufficient.
 Allow the bearings to cool before tightening the screws.
NOTICE
Mounting forces must only be applied to the bearing ring to be fitted
and never through the rolling elements. Avoid direct blows on
the bearing rings in all cases. Bearing rings must be fitted without
the use of external loads.
When fitting the inner ring, direct forces only through the inner ring.
When fitting the outer ring, direct forces only through the outer ring.
Bearing components must not be separated or interchanged during
fitting and dismantling.

Locating the bearing inner ring  The seating surfaces for the bearing inner rings on the adjacent
construction should be lightly oiled or rubbed with solid lubricant.
 Loosen the retaining screws (2 or 3, depending on the bearing)
by between half a revolution and one full revolution.
For ZKLDF bearings, loosen the retaining screws so that the two
inner rings can centre themselves in relation to each other.
 Once the retaining screws have been removed, the bearing
arrangement is no longer self-retaining.
 Retaining screws
Figure 7
Loosening the retaining screws
0000BE710000BE71

16 MON 100 Schaeffler Technologies
High precision bearings for combined loads
 Before the bearing is pushed into place, align the hole pattern
in the bearing to the hole pattern in the adjacent construction.
For example, threaded rods can be used.
 Push the bearing onto the shaft, taking care not to tilt the bearing.
 Insert the fixing screws in the holes and tighten finger tight.
In the case of axial angular contact ball bearings ZKLDF,
rotate the unlocated bearing ring. This will centre the inner rings.
 Tighten the fixing screws in a crosswise sequence using a torque
wrench in three stages to the specified tightening torque M
A
.
In the case of axial angular contact ball bearings ZKLDF,
rotate the bearing ring.
Tighten the fixing screws in three stages using different tightening
torques, see page 18:
■ stage 1: 40% of M
A
■ stage 2: 70% of M
A
■ stage 3: 100% of M
A
 After fitting of the bearings, retighten or remove the retaining
screws.
Figure 8
Rotating the unlocated bearing ring
0000BE870000BE87
Figure 9
Locating the inner ring
0000BE8A0000BE8A

Schaeffler Technologies MON 100 17
Locating the bearing outer ring  The seating surface for the bearing outer ring in the housing
should be lightly oiled or rubbed with solid lubricant.
 Fit the outer ring of the bearing and shaft assembly in the housing
bore.
 Insert the fixing screws in the holes and tighten in a crosswise
sequence using a torque wrench in three stages to the specified
tightening torque M
A
.
Tighten the fixing screws in three stages using different tightening
torques, see page 18:
■ stage 1: 40% of M
A
■ stage 2: 70% of M
A
■ stage 3: 100% of M
A
Figure 10
Insert the outer ring
into the housing bore
0000BE8D0000BE8D
Figure 11
Locating the outer ring
0000BE790000BE79

18 MON 100 Schaeffler Technologies
High precision bearings for combined loads
NOTICE
All the fixing screw holes must be used. If a smaller number of
fixing screws is used, this will reduce the load carrying capacity of
the screw connections as well as the running accuracy and rigidity of
the bearing.

The rigidity values in the dimension tables of TPI 120, High Precision
Bearings for Combined Loads, and in Catalogue HR 1, Rolling
Bearings, are only valid if all the fixing holes are used.
In order to prevent unacceptable variations between the screw
tensioning forces, adhere exactly to the fixing sequence (tighten
the screws in a crosswise sequence).
Tightening torques M
A
for
axial/radial bearings
1)
Tightening torque M
A
for fixing screws to DIN EN ISO 4762, grade 10.9.
Bore
diameter
Fixing screw Tightening torque
1)
M
A
Nm
Stage
1 2 3
mm 40% of M
A
70% of M
A
100% of M
A
50 M5 368,5
80 M4 334,5
80 M5 368,5
100 M5 368,5
120 M6 610 14
150 M6 610 14
180 M6 610 14
200 M6 610 14
260 M8 14 24 34
325 M8 14 24 34
395 M8 14 24 34
460 M8 14 24 34
580 M10 27 48 68
650 M12 46 81 116
850 M16 114 199 284
950 M16 114 199 284
1030 M16 114 199 284