The RU228 cross roller bearing is a high-rigidity precision bearing with a 160 mm bore, 295 mm outside diameter and 35 mm width. Its integrated inner and outer rings include mounting holes, allowing the bearing to be installed directly without separate housings or clamping flanges in many rotary systems.
With dynamic and static load ratings of 104 kN and 173 kN, RU228 is designed for large robot bases, heavy-duty positioners, rotary indexing tables, hollow direct-drive axes and precision inspection platforms. The large center bore provides useful routing space for shafts, cables, pneumatic lines or other services.
LYDL supplies RU228, RU228G and RU228X mounting configurations with open or sealed structures, CC0/C0/C1 clearance options and P5, P4 or P2 accuracy grades. Dimensional inspection reports, matched lubrication, export packaging and application-based selection support are available for OEM and replacement projects.
RU228 Cross Roller Bearing | Reliable 160×295×35 mm
The RU228 cross roller bearing is a precision crossed roller bearing with integrated mounting holes in both rings. Cylindrical rollers are arranged alternately at right angles, allowing one compact bearing to support radial loads, axial loads and overturning moments.
Compared with smaller RU models, RU228 provides a larger 160 mm hollow bore and higher load capacity for heavy rotary structures. The integrated inner and outer rings help simplify surrounding components while maintaining the rigidity required by robot joints, positioners and precision indexing systems.
Explore the complete RU cross roller bearing series or visit our cross roller bearing category for alternative structures.
RU228 Cross Roller Bearing Specifications
Parameter
RU228 specification
Bore diameter, d
160 mm
Outside diameter, D
295 mm
Bearing width, B
35 mm
Roller pitch circle diameter, dp
227.5 mm
Basic dynamic load rating, C
104 kN
Basic static load rating, C₀
173 kN
Approximate mass
11.4 kg
Maximum shoulder diameter, ds
208 mm maximum
Minimum housing shoulder diameter, Dh
246 mm minimum
Minimum fillet radius, r
2 mm
Greasing-hole diameter, d₁
6 mm
Inner-ring bolt-circle diameter
184 mm
Outer-ring bolt-circle diameter
270 mm
Inner-ring mounting holes
12 holes
Outer-ring mounting holes
12 holes
Available accuracy
P5, P4 or P2
Available clearance
CC0, C0 or C1
Sealing options
Open, UU, U or UT
Optional grease nipple
NP6×5
Load ratings are reference catalog values. Final life, rigidity and safety-factor calculations should use the confirmed operating load spectrum, moment arm, speed, lubrication, installation accuracy and LYDL-approved drawing.LYDL RU228 cross roller bearing with integrated inner- and outer-ring mounting holes.
RU228 Design Advantages
Large 160 mm Hollow Bore
The 160 mm center opening can accommodate a reducer output, direct-drive rotor, drive shaft, cables, pneumatic tubes or hydraulic lines. This makes RU228 particularly useful where services must pass through the rotary axis.
The available opening must still be checked after considering shoulders, fasteners, cable carriers and the required installation tools.
Integrated Mounting Structure
Both bearing rings contain mounting holes, so the RU228 cross roller bearing can often be bolted directly to the rotating member and machine frame. This can reduce the number of housing components and shorten the tolerance chain.
Direct mounting does not eliminate the need for a rigid supporting structure. Uneven mounting faces or flexible plates can distort the raceways and reduce rotational accuracy.
Combined-Load Capability
The crossed roller arrangement supports loads from multiple directions in one bearing position. RU228 is therefore suitable for rotary axes exposed to simultaneous radial load, axial thrust and overturning moment.
For applications with an offset payload, provide the payload, distance from the bearing center, acceleration and emergency-stop conditions rather than selecting from vertical load alone.
Inner- and outer-ring counterbores face the same direction
Convenient when both bolt heads are accessible from one assembly side
RU228G
Inner- and outer-ring counterbores face opposite directions
Useful when the rings are fastened from opposite sides
RU228X
Inner ring has 12 × M10 threaded through holes; outer ring has 12 × Ø11 through holes with Ø17.5 counterbores, 10.8 mm deep
Selected when bolts must engage directly with the inner ring
For standard RU228 and RU228G arrangements, the reference mounting pattern uses 12 × Ø11 through holes with Ø17.5 counterbores, 10.8 mm deep, on each ring. Counterbore orientation changes between the standard and G configurations.
Do not select RU228G or RU228X from the suffix alone. Confirm the counterbore direction, threaded-hole location, bolt-entry side and adjacent-component drawing before ordering.
Seal, Clearance and Accuracy Codes
A complete designation may combine the base model with seal, clearance, accuracy and mounting codes. A typical configured order could be written as: RU228 / UU / CC0 / P4 / B / G / -N
Code
Meaning
No seal code
Open bearing
UU
Seals on both sides
U
One seal on the outer-ring counterbore side
UT
One seal on the side opposite the outer-ring counterbore
CC0
Controlled negative-clearance/preload range
C0
Normal reference clearance range
C1
Larger specified clearance range
P5 / P4 / P2
Increasing rotational-accuracy requirements
No R or B code
Accuracy designation referenced to inner-ring rotation
R
Accuracy designation referenced to outer-ring rotation
B
Accuracy requirements applied to both rings
G
Opposite counterbore orientation
X
Threaded inner-ring mounting holes
-N
Grease nipple supplied; NP6×5 applies to RU228
The appropriate clearance and accuracy combination depends on rotational accuracy, torque, thermal conditions and mounting deformation. Confirm the complete designation on the quotation and approved drawing; do not assume that every suffix combination is held in stock.
RU228 Cross Roller Bearing Applications
The RU228 cross roller bearing is commonly considered for:
Large industrial robot bases and primary rotary joints
Welding, assembly and heavy-duty workpiece positioners
CNC rotary tables and large indexing axes
Hollow-shaft direct-drive motors
Reducer output supports and precision slewing mechanisms
Metrology, scanning and optical inspection platforms
Antenna, sensor and observation-system positioners
Semiconductor or automation equipment requiring a large cable-routing bore
In robot bases and positioners, RU228 offers more central routing space and higher load ratings than RU178. In large indexing equipment, its performance depends strongly on the flatness and rigidity of the base plate under moment loading.Typical RU series applications include compact robots, rotary actuators, inspection systems and laboratory automation
Larger machinery requiring a 210 mm bore and higher ratings
These ratings should not be used as the only selection criterion. Compare the real load spectrum, overturning moment, mounting space, rigidity target, rotational accuracy and operating temperature.
For more selection principles, see the cross roller bearing selection guide.
Need an RU228 Drawing or Quick Quotation?
If the required model is already known, send us the RU228, RU228G or RU228X designation, quantity, accuracy grade, sealing requirement and delivery destination.
If the selection is not finalized, provide the radial and axial loads, overturning moment or moment arm, speed, duty cycle, mounting envelope and working environment. Request an RU228 technical review and quotation
Brand Reference and Interchange Guidance
THK RU228, RU228G and RU228X designations may be used as dimensional references when identifying an existing bearing. However, matching the nominal 160 × 295 × 35 mm dimensions alone does not establish full interchangeability.
Before replacing another brand, compare:
Bearing width and shoulder dimensions
Inner- and outer-ring bolt-circle diameters
Hole diameter, quantity and counterbore orientation
Threaded-hole position
Seal arrangement
Internal clearance or preload
Rotational accuracy and controlled ring
Grease-hole position
Load ratings and permissible operating conditions
A direct one-to-one IKO CRBF/CRBFV model for RU228 has not been confirmed in the cited comparison range. A “CRBF-style 160 × 295 × 35 mm bearing” should therefore be treated only as a structural description—not as a verified model interchange. Send the original drawing, label and application data for engineering comparison.
THK and IKO names and designations are trademarks or product references belonging to their respective owners. They are used here solely for identification and technical comparison. LYDL is an independent bearing supplier and does not claim affiliation with or endorsement by these brands.
Engineering Standards and Technical References
The following references improve consistency in bearing terminology, rating calculations, tolerances and failure analysis:
THK Model RU technical data — reference dimensions, mounting-hole arrangements, suffixes and nominal load ratings: THK Model RU Technical PDF
THK RU product overview — reference description of the integrated inner- and outer-ring structure: THK Cross-Roller Ring Model RU
IKO crossed roller bearing catalog — used for structural and catalog-range comparison, not as proof of direct interchange: IKO Crossed Roller Bearings Catalog
ISO 281:2007 — rolling bearings, dynamic load ratings and rating life: ISO 281:2007
ISO 76:2006 — rolling bearings and static load ratings: ISO 76:2006
ISO 492:2023 — radial bearing geometrical product specifications and tolerance values: ISO 492:2023
ISO 15:2017 — radial bearing boundary dimensions and general plan: ISO 15:2017
ISO 15243:2017 — classification of rolling-bearing damage and failures: ISO 15243:2017
These references establish common engineering terminology and calculation frameworks. They do not replace the application-specific LYDL drawing, inspection agreement or confirmed order specification.
RU228 Installation Recommendations
Control Mounting-Face Deformation
For RU228, base and rotating plates should be sufficiently rigid to distribute bolt forces without local bending. Large bolt circles can still deform when mounted to thin, interrupted or poorly supported structures.
Inspect mounting surfaces for flatness, burrs, contamination and raised material around threaded holes. Tightening the bearing against an uneven face can change running torque and accuracy.
Use a Controlled Bolt Sequence
Install fasteners gradually in a diagonal or cross pattern. Apply torque in several stages rather than fully tightening adjacent bolts one after another.
Fastener grade, engagement length and final torque must be determined from the customer’s joint design. Do not use a generic torque value without considering thread material, lubrication and interface requirements.
Handle the 11.4 kg Bearing Safely
Use suitable lifting or positioning support during installation. Do not lift the bearing by its seals or grease nipple, and do not place concentrated loads on the ring edges.
Keep the bearing horizontal and adequately supported whenever practical. Impact loading, dropping or forcing the rings into alignment may damage the precision raceways.
Verify Lubrication Access
RU228 uses 6 mm reference greasing holes and can be configured with an NP6×5 grease nipple. Confirm that the grease point remains accessible after surrounding plates, covers and drives are installed.
For low-speed oscillation or limited rotation, verify that lubricant can reach the working roller zone. Relubrication intervals should be based on temperature, load, speed, stroke and contamination—not calendar time alone.
Run-In and Monitor
After mounting, rotate the system slowly and check for abnormal torque, noise, temperature rise or binding. Increase operating speed and load progressively while monitoring the assembly.
RU228 is primarily selected for rigidity, combined-load capacity and positioning performance. Continuous high-speed use requires separate verification of grease, seals, preload, heat generation and drive torque.
Inspection and Export Packaging
LYDL inspection for an RU228 cross roller bearing can include:
Bore, outside diameter and width inspection
Bolt-circle and mounting-hole verification
Counterbore direction or threaded-hole confirmation
Radial clearance or configured preload checks
Rotational accuracy and running-torque inspection
Seal and lubrication-point inspection
Appearance, marking and designation verification
Inspection report and photo documentation when specified
For export shipment, the bearing is cleaned, protected against corrosion, sealed against moisture and packed in a reinforced carton or wooden case according to quantity and transport conditions. The packaging method should prevent unsupported movement and edge impact during handling.dimensional inspection, rotation testing and protective export packaging at LYDL.
Why Source RU228 from LYDL?
RU228, RU228G and RU228X mounting configurations
Open, UU, U and UT sealing options
CC0, C0 and C1 clearance specifications
P5, P4 and P2 precision capability
Dimensional and rotational inspection documentation
Small-batch OEM and replacement-order support
Application review based on load, moment, rigidity and installation space
Export packaging and international shipment support
RU228 Cross Roller Bearing FAQ
Why is mounting-plate rigidity especially important for RU228?
RU228 has a 295 mm outside diameter and a relatively large bolt circle. If the supporting plate bends between fasteners, tightening can distort the bearing rings and change running torque or rotational accuracy. Plate thickness, ribs, material and foundation stiffness should be evaluated together.
Can the 160 mm bore carry cables through a hollow rotary axis?
Yes. The large bore is useful for cables, pneumatic lines, hydraulic tubes or a hollow drive shaft. However, the effective routing envelope is smaller after accounting for shoulders, bolts, connectors, cable bend radius and installation clearance.
When should RU228G be selected instead of standard RU228?
Choose RU228G when the inner- and outer-ring counterbores need to face opposite directions because the two rings are fastened from different sides. Confirm bolt-entry access on the assembly drawing before ordering.
What is the main advantage of RU228X?
RU228X provides 12 M10 threaded through holes in the inner ring. It is useful when bolts must engage directly with the inner ring and a nut or rear-side tool cannot be used. The outer ring retains through holes with counterbores.
Does RU228 require special handling during assembly?
At approximately 11.4 kg, it should be supported securely and kept free from impact. Do not suspend it from a seal or grease fitting. Lifting and positioning methods must also protect the precision mounting faces and ring edges.
Is RU228 suitable for continuous high-speed rotation?
It may be used in rotating equipment, but it is generally selected for rigidity, moment capacity and precision rather than maximum speed. Speed capability depends on load, clearance or preload, seal drag, grease, cooling and acceptable temperature rise.
Is there a direct IKO equivalent for RU228?
No direct one-to-one IKO CRBF or CRBFV reference has been confirmed from the cited catalog range. Compare the complete bearing drawing, mounting holes, accuracy, clearance, seals and load ratings before treating another product as interchangeable.
When should RU297 be considered instead?
Consider RU297 when the system requires a larger 210 mm center bore, higher nominal load ratings or a larger supporting footprint. RU228 remains the more compact choice when its 160 mm bore and calculated capacity meet the design requirements.
