RU178 Cross Roller Bearing | 115×240×28 mm

RU178 Cross Roller Bearing Overview

The RU178 cross roller bearing is an integrated, mounting-holed precision bearing for rotary systems requiring a larger hollow passage, higher load capacity and greater moment-supporting geometry than RU148. Its principal dimensions are 115 mm bore, 240 mm outside diameter and 28 mm width. Cylindrical rollers are arranged alternately at 90 degrees, enabling one bearing to support radial loads, axial loads in both directions and overturning moments. As part of the RU series crossed roller bearings, the RU178 cross roller bearing has mounting holes on both rings. It can be installed directly onto accurately machined supporting components, reducing the need for separate bearing housings and clamping flanges.

Key RU178 Advantages

• Integrated inner and outer rings
• Large 115 mm hollow center
• 178 mm roller pitch diameter
• 80.3 kN dynamic radial load rating
• 135 kN static radial load rating
• Twelve mounting positions on each ring
• RU178, RU178G and RU178X configurations
• Open, one-side-sealed and double-sealed options
• Suitable for inner- or outer-ring rotation

RU178 Cross Roller Bearing Specifications

The stated RU178 cross roller bearing ratings are radial catalog values. They should not be interpreted as the maximum combined load or allowable overturning moment of the complete machine. Bearing life and static safety depend on the actual radial load, axial load, moment arm, shock factor, speed, duty cycle, preload, lubrication and mounting rigidity.  

RU178 Cross Roller Bearing Design Characteristics

Large Hollow Passage

The 115 mm bore provides space for hollow reducer outputs, drive shafts, electrical cables, pneumatic lines, hydraulic connections or coolant routing. The complete nominal bore should not be treated as usable service space. Clearance must be allowed for shafts, cable movement, bend radius, protective sleeves and manufacturing tolerances.

Increased Moment-Supporting Geometry

The 178 mm roller pitch diameter provides a wider supporting geometry than RU148. This is beneficial in robot bases, positioners and rotary platforms carrying offset loads. The applied moment should be calculated from both force and distance from the bearing center. A modest load acting through a long lever arm can create a substantial overturning moment.

Twelve-Position Mounting Pattern

Each ring has twelve equally spaced mounting positions. Correctly designed fastening can distribute operating loads around the bearing, but the mounting plate must be sufficiently rigid to maintain the bearing geometry.

Integrated Ring Construction

Both rings are integrated, reducing sensitivity to ring separation during handling. Direct mounting can also reduce component count and tolerance accumulation. Explore the complete cross roller bearing range when a different mounting method or split-ring structure is required.

RU178 Cross Roller Bearing Mounting Variants

All three versions use the same principal dimensions and reference load ratings. Their mounting-hole arrangements differ.

Selecting the Correct Version

• Choose RU178 when inner- and outer-ring fasteners can be accessed from the same assembly side.
• Choose RU178G when the two sets of fasteners must be inserted from opposite sides.
• Choose RU178X when bolts need to engage directly with M8 threads in the inner ring.

Confirm the variant before machining the housing, output flange or bolt-access openings.

Seal, Clearance, Accuracy and Lubrication Codes

Without an R or B designation, the standard model convention normally controls inner-ring rotational accuracy. Confirm the accuracy-critical rotating ring with LYDL before ordering. A detailed specification may be written as: RU178 / UU / CC0 / P4 / B / G / -N This identifies a double-sealed, preloaded, P4-grade RU178G with controlled running accuracy for both rings and an optional grease nipple. The approved LYDL drawing and purchase order remain the final authority for all model codes.

RU178 Cross Roller Bearing Applications

Robot Bases and Large Rotary Joints

RU178 can support combined loads in robot bases, shoulder joints and large rotary axes. The 115 mm center opening can accommodate a hollow reducer output, wiring and service lines. Emergency-stop loads, robot reach, payload position and acceleration should be included in the selection calculation.

Welding and Assembly Positioners

The bearing is suitable for positioners carrying fixtures or workpieces at an offset from the rotary center. Both working load and fixture overhang contribute to overturning moment.

CNC Rotary and Tilting Axes

Controlled preload and high rigidity support indexing, positioning and inspection operations. Cutting-force applications require additional evaluation of shock loads and mounting stiffness.

Precision Industrial Platforms

RU178 can be used in optical inspection platforms, medical positioning mechanisms, radar or sensor rotation systems and automated assembly equipment requiring a large central passage.

Selecting RU148, RU178 or RU228

• Select the RU148 cross roller bearing when a 90 mm bore and smaller 210 mm outside diameter are sufficient.
• Select RU178 when a 115 mm passage and considerably higher static-load capacity than RU148 are required.
• Select the RU228 cross roller bearing when a 160 mm passage, larger bolt circle or higher load ratings are necessary.

This comparison supports preliminary selection only. Refer to the cross roller bearing selection guide and complete an application-specific load, life and rigidity review before final approval.

Need an RU178 Drawing or Quick Quotation?

If the required model is already known, send the RU178, RU178G or RU178X designation, quantity, accuracy grade, seal arrangement and delivery country. If the model has not been finalized, send the radial load, axial load, moment arm, speed, duty cycle and available installation dimensions. Request an RU178 technical review and quotation from the LYDL engineering team.

RU178 Cross Roller Bearing Interchange Reference

The references indicate a similar 115 × 240 × 28 mm envelope and mounting concept. They do not establish automatic interchangeability. For example, an IKO CRBFV11528AT reference may specify:

• Dynamic radial load rating of approximately 84.3 kN
• Static radial load rating of approximately 138 kN
• Outer-ring counterbore depth of 13.5 mm

The RU178 reference data used on this page specifies:

• Dynamic radial load rating of 80.3 kN
• Static radial load rating of 135 kN
• Counterbore depth of 8.6 mm

These differences must be reviewed before approving a replacement. THK and IKO are trademarks of their respective owners. They are mentioned only for model identification and technical comparison. LYDL is an independent manufacturer and is not affiliated with or endorsed by these companies.

Engineering Standards Relevant to RU178

• ISO 281 provides general methods for dynamic load ratings and basic rating-life calculations.
• ISO 76 covers static load ratings, static equivalent loads and static safety evaluation.
• ISO 492 provides general dimensional and geometrical tolerance terminology for radial rolling bearings.
• ISO 15243 standardizes terminology for bearing damage, characteristics and possible failure causes.

These standards provide calculation and terminology frameworks. They do not replace the RU178 catalog data, approved drawing or application-specific engineering analysis.

RU178 Cross Roller Bearing Installation

RU178 is frequently used under substantial overturning moment. The mounting plates and bolt connections must therefore be evaluated as part of the complete rotary support.

1. Clean the bearing, mounting faces and locating shoulders.
2. Remove burrs from bolt holes and counterbores.
3. Confirm the 139 mm and 217 mm mounting PCDs.
4. Verify whether RU178, RU178G or RU178X is required.
5. Check counterbore direction and bolt-access space.
6. For RU178X, confirm M8 thread engagement and bolt length.
7. Lower the bearing into position without impact.
8. Install all twelve fasteners loosely before final tightening.
9. Tighten the fasteners gradually in a diagonal sequence.
10. Rotate the bearing during staged tightening.
11. Measure radial and axial runout after assembly.
12. Record starting and running torque.
13. Monitor temperature during initial operation.

A universal bolt torque is not stated because the correct value depends on bolt grade, thread engagement, mounting material, surface treatment and lubrication condition. If the supporting plate deforms under load, selecting a higher bearing accuracy grade alone will not correct the resulting system error.

RU178 Cross Roller Bearing Inspection and Packaging

LYDL can inspect RU178 according to the selected variant, accuracy, preload and documentation requirements.

Available Inspection Items

• Bore, outside diameter and width
• Mounting-hole position and PCD
• Counterbore diameter, depth and orientation
• M8 thread inspection for RU178X
• Ring roundness and raceway geometry
• Material hardness
• Radial clearance or preload
• Starting and running torque
• Radial and axial runout
• Rotation smoothness and noise
• Seal, model and serial-number verification

Inspection reports, material certificates and traceability records can be provided when requested before production. After inspection, each bearing receives suitable anti-rust protection. Packaging options include sealed or vacuum bags, shock-resistant material, individual cartons and reinforced export plywood cases.

Why Source an RU178 Cross Roller Bearing From LYDL?

LYDL manufactures precision crossed roller bearings in Luoyang, China. Production and inspection capabilities cover ring machining, heat treatment, raceway grinding, superfinishing, component sorting, cleaning, assembly, preload verification and final inspection. Available RU178 options include:

• RU178, RU178G and RU178X mounting designs
• Open, U, UT and UU sealing
• P5, P4 and P2 accuracy
• Inner-ring, outer-ring or both-ring accuracy control
• Controlled clearance or preload
• Special grease and optional grease nipple
• OEM marking and serial numbers
• Material, dimensional and runout reports

RU178 Cross Roller Bearing FAQ

How should emergency-stop loading be considered for a robot base?

Emergency stopping can produce higher inertial force and overturning moment than normal operation. Include the robot reach, payload position, acceleration and stopping profile in the static safety review.

Does the 115 mm bore improve robot cable routing?

Yes. The larger opening provides useful internal routing space, but allowance is still required for cable movement, bend radius, protective sleeves and connectors.

Why can a flexible mounting plate reduce RU178 accuracy?

Plate deformation can tilt or distort the bearing rings, changing roller-load distribution and installed runout. The bearing, plates and bolts should be treated as one structural system.

Does RU178 require finite-element analysis?

Not for every installation. FEA is useful when mounting plates are thin, payloads are highly offset, stiffness targets are strict or the load path is difficult to estimate using simplified calculations.

Can RU178 operate continuously at high speed?

RU178 is primarily intended for high rigidity, combined loads and precision rotary motion. Continuous speed depends on load, preload, seals, lubricant, heat dissipation and acceptable temperature rise.

When is RU178X preferable to RU178G?

Choose RU178X when bolts must engage directly with M8 threads in the inner ring. Choose RU178G when both rings use counterbored through holes but the counterbores must face opposite directions.

Can CRBFV11528AT directly replace RU178X?

Not automatically. Although the principal dimensions and inner-ring thread pattern are similar, counterbore depth, load ratings, clearance codes, seals and internal specifications can differ.

Request a Reliable RU178 Cross Roller Bearing Quote

For accurate selection and pricing, provide:

• RU178, RU178G or RU178X
• Required quantity
• Seal arrangement
• Rotating ring
• Radial and axial loads
• Moment arm
• Speed and duty cycle
• Accuracy grade
• Clearance or preload
• Lubrication and temperature
• Required inspection documents

Email sales@luoyangdeeplink.com with your model, drawing or operating conditions. LYDL can provide dimensional confirmation, variant review, production lead time and an export quotation.

Technical References and Citation Scope

1. THK—Cross-Roller Ring Standard Models RU, RU-H and RUV Used for integrated-ring structure, high rigidity and inner- or outer-ring rotation characteristics.
2. THK—Model RU Dimensional and Model-Code Table Used for RU178 dimensions, load ratings, mounting variants, seal codes, accuracy symbols and grease-nipple designation.
3. IKO—CRBFV11528AT Open-Type Product Data Used to compare the threaded-inner-ring configuration, principal dimensions and IKO catalog ratings.
4. IKO—CRBF Crossed Roller Bearing Catalog Used for cross-brand mounting-hole, counterbore and load-rating comparison.
5. ISO 281:2007—Rolling Bearings: Dynamic Load Ratings and Rating Life Used as a general reference for dynamic load-rating and rating-life principles.
6. ISO 76:2006—Rolling Bearings: Static Load Ratings Used as a general reference for static equivalent load and static safety evaluation.
7. ISO 492:2023—Rolling Bearings: GPS and Tolerance Values Used for general dimensional and geometrical tolerance terminology.
8. ISO 15243:2017—Rolling Bearings: Damage and Failures Used for standardized bearing-damage terminology and possible failure causes.

These references support dimensional comparison, terminology and general engineering principles. They do not replace the approved LYDL drawing, inspection agreement or application-specific engineering review.

Explore this bearing series

RU Series Integrated Cross Roller Bearings · Series dimensions and selection guide

Published RU model pages

RU85 · RU66 · RU42 · RU124 · RU148 · RU178 · RU228 · RU52 · RU28 · RU297