Crossed Roller Slewing Bearings

Crossed roller slewing bearings feature cylindrical rollers arranged at a 90° V-groove mutually at right angles through a spacer. This orthogonal configuration allows a single bearing position to accommodate simultaneous radial loads, axial loads, and overturning moments. Applied primarily in heavy rotary joints, industrial robots, medical imaging equipment, and precision rotary tables, they eliminate the need for multi-bearing combinations, saving structural space in demanding spatial constraints. 

The internal assembly comprises an outer ring, an inner ring, a full complement of cylindrical rollers, and precision spacers.

Roller Layout: Rollers alternate at 90° orientation along the raceway, enabling line contact with raceway surfaces.

Spacer Integration: Plastic or brass spacers between individual rollers minimize friction torque and prevent roller skewing during high-speed directional shifts.

Integral vs. Split Configurations: Inner or outer rings are offered in integrated single-piece designs or split-ring structures secured after roller insertion, accommodating pre-load adjustment during assembly.

Combined Load Capacity: Handles axial, radial, and moment loads concurrently without requiring multi-bearing sets.

High Rotational Rigidity: Orthogonal roller arrangement reduces elastic deformation under heavy loads, ensuring stable runout tolerance.

Compact Footprint: Low sectional height reduces radial and axial dimensions of host assemblies.

Zero-Clearance Preload Capability: Internal radial and axial clearance can be adjusted via mounting bolts and shims to achieve negative clearance (preload), eliminating backlash.

Toothless (Non-geared): Relies on external drive mechanisms (e.g., dual pinions, belt drives) or friction clamping; suited for compact joints where gear cutting on the ring is structurally restricted.

Internal-Toothed: Gear teeth are machined directly onto the inner ring. The drive pinion sits inside the bearing envelope, protecting the gear mesh from external debris and minimizing the overall machine footprint.

External-Toothed: Gear teeth are machined on the outer ring periphery. Facilitates larger pitch circle diameters for higher output torque transmission and simplifies gearbox alignment with external drive motors.

Load Rating Verification: Dynamic equivalent load (P=XFr​+YFa) and static safety factor (Ss​=P0​C0​​≥1.5) must be verified against maximum operational overturning moments.

Speed Limitations: Limiting rotational speed depends on lubrication type and cage construction; grease-lubricated units generally operate up to 50% of the limiting speed of oil-lubricated variants.

Fit and Tolerance: Housing bores require H7/J7 tolerances; shaft seats require h6/j6 tolerances to prevent raceway distortion.

Mounting Surface Flatness: Mating structure flatness must remain within 0.01 mm to 0.03 mm depending on bearing diameter to avoid uneven preload distribution.

Industrial Robotics: Joint actuators of articulated robots, SCARA robots, and collaborative robot bases requiring high torsional rigidity.

Precision Rotary Tables: CNC index tables, optical rotary stages, and milling machine dividing heads.

Medical Equipment: C-arm medical imaging systems, CT scanners, and surgical robot gimbals.

Defense & Aerospace: Radar antenna pedestals, optical tracking turrets, and missile launch platforms.

Preparation: Clean mounting surfaces thoroughly; remove burrs, rust preventative oils, and particulate matter using solvent cleaners.

Bolt Tightening Sequence: Use high-strength socket head cap screws (Property Class 12.9). Tighten mounting bolts progressively in a cross-pattern sequence using a calibrated torque wrench.

Preload Adjustment: For split-ring designs, measure starting torque during gradual bolt tightening to achieve the specified rotational resistance.

Alignment Check: Measure axial and radial runout of the mounted assembly using dial indicators before final operational commissioning.

Raw Material Testing: Spectrometric analysis and ultrasonic testing verify inclusion cleanliness and hardenability of GCr15 steel bars.

Dimensional Metrology: Coordinate Measuring Machines (CMM) inspect raceway depth, mounting hole pitch, and gear tooth profiles (module, pressure angle, tooth thickness).

Nondestructive Testing (NDT): Magnetic particle inspection (MPI) detects surface and subsurface micro-cracks on raceways and gear teeth following heat treatment.

Functional Testing: Automated test benches measure starting friction torque, radial runout, and axial play under simulated load conditions.

Packaging: Industrial rust-inhibiting VCI plastic wrapping, packed in heavy-duty export-grade plywood crates with foam securing brackets to prevent transit shock.

Lead Time: Stock configurations ship within 3 to 5 business days; custom non-standard, toothed, or high-precision (P4/P2) units require 4 to 6 weeks manufacturing lead time.

Customization: Custom mounting hole patterns, specialized corrosion-resistant surface coatings (e.g., black oxide, chrome plating), and high-temperature grease fill options available upon engineering review.