What is a crossed roller bearing?
A crossed roller bearing has one row of cylindrical rollers between an inner ring and an outer ring. Neighbouring rollers are set at 90° to each other, so half of the rollers carry axial load in one direction and half in the other. One bearing therefore supports radial load, axial load in both directions and tilting moment at the same time.
A single bearing that carries all three load types lets a rotary axis be built shorter than one with two spaced bearings. That is why crossed roller bearings sit in robot joints and wrists, rotary and index tables, medical equipment and measuring instruments.
RAU series: full dimension table
All 28 RAU sizes with boundary dimensions, shoulder diameters, load ratings and mass. ds is the shaft shoulder diameter and Dh the housing shoulder diameter for each size. r min is the minimum chamfer. C and C0 are the basic dynamic and static radial load ratings.
| Model | d | D | B | r min | ds | Dh | C (N) | C0 (N) | Mass (kg) |
|---|
| RAU1005 | 10 | 21 | 5 | 0.15 | 12.5 | 17 | 1120 | 800 | 0.009 |
| RAU1505 | 15 | 26 | 5 | 0.15 | 17.5 | 22 | 1320 | 1100 | 0.012 |
| RAU2005 | 20 | 31 | 5 | 0.15 | 22.5 | 27 | 1490 | 1400 | 0.015 |
| RAU3005 | 30 | 41 | 5 | 0.15 | 32.5 | 37 | 1890 | 2140 | 0.021 |
| RAU4005 | 40 | 51 | 5 | 0.15 | 42.5 | 47 | 2140 | 2740 | 0.027 |
| RAU4008UU | 40 | 56 | 8 | 0.5 | 43.5 | 50.5 | 4320 | 5650 | 0.058 |
| RAU5005 | 50 | 61 | 5 | 0.15 | 52.5 | 57 | 2430 | 3490 | 0.032 |
| RAU5008UU | 50 | 66 | 8 | 0.5 | 53.5 | 60.5 | 5100 | 7190 | 0.08 |
| RAU6005 | 60 | 71 | 5 | 0.15 | 62.5 | 67 | 2630 | 4090 | 0.038 |
| RAU6008UU | 60 | 76 | 8 | 0.5 | 63.5 | 70.5 | 5680 | 8680 | 0.09 |
| RAU7005 | 70 | 81 | 5 | 0.15 | 72.5 | 77 | 2810 | 4680 | 0.044 |
| RAU7008UU | 70 | 86 | 8 | 0.5 | 73.5 | 80.5 | 5980 | 9800 | 0.1 |
| RAU8005 | 80 | 91 | 5 | 0.15 | 82.5 | 87 | 3050 | 5430 | 0.05 |
| RAU8008UU | 80 | 96 | 8 | 0.5 | 83.5 | 90.5 | 6370 | 11300 | 0.11 |
| RAU9005 | 90 | 101 | 5 | 0.15 | 92.5 | 97 | 3190 | 6030 | 0.056 |
| RAU9008UU | 90 | 106 | 8 | 0.5 | 93.5 | 100.5 | 6760 | 12400 | 0.12 |
| RAU10005 | 100 | 111 | 5 | 0.15 | 102.5 | 107 | 3370 | 6630 | 0.06 |
| RAU10008UU | 100 | 116 | 8 | 0.5 | 103.5 | 110.5 | 7150 | 13900 | 0.14 |
| RAU11008UU | 110 | 126 | 8 | 0.5 | 113.5 | 120.5 | 7450 | 15000 | 0.15 |
| RAU12008UU | 120 | 136 | 8 | 0.5 | 123.5 | 130.5 | 7840 | 16500 | 0.17 |
| RAU13008UU | 130 | 146 | 8 | 0.5 | 133.5 | 140.5 | 7940 | 17600 | 0.18 |
| RAU14008UU | 140 | 156 | 8 | 0.5 | 143.5 | 150.5 | 8330 | 19100 | 0.19 |
| RAU15008UU | 150 | 166 | 8 | 0.5 | 153.5 | 160.5 | 8820 | 20600 | 0.2 |
| RAU16013UU | 160 | 186 | 13 | 0.8 | 165 | 179 | 23300 | 44900 | 0.59 |
| RAU17013UU | 170 | 196 | 13 | 0.8 | 175 | 189 | 23500 | 46500 | 0.64 |
| RAU18013UU | 180 | 206 | 13 | 0.8 | 185 | 199 | 24500 | 49800 | 0.68 |
| RAU19013UU | 190 | 216 | 13 | 0.8 | 195.5 | 209 | 24900 | 51500 | 0.69 |
| RAU20013UU | 200 | 226 | 13 | 0.8 | 205 | 219 | 25800 | 54700 | 0.71 |
The 8 mm and 13 mm wide sizes are listed with the UU suffix, the sealed version. Order with the full designation.
What we need for selection
- Which ring rotates, and whether the motion is continuous rotation or oscillation.
- Radial load, axial load and tilting moment, with the distance from the load point to the bearing.
- Speed or oscillation angle and frequency, shock, temperature and contamination.
- Running accuracy, starting and running torque, clearance or preload.
- Shaft, housing and clamping-ring drawings.
The load ratings in the table are for initial selection. Life, speed and stiffness depend on the mounting and the duty, so we review them on your drawing before quoting.
Mounting thin-section crossed roller bearings
The rings are thin, so they take the shape of the parts around them. Flatness and squareness of the shoulders, the fit and the clamping force all show up in the running torque and runout of the assembled axis.
- Clean the shaft, housing and clamping rings. Remove burrs from every contact face.
- Seat the bearing square against the shoulder. Do not drive it in by striking one ring.
- Tighten the clamping screws in a cross pattern, in several steps, up to the final torque.
- Check rotation torque and runout after clamping, not only on the free bearing.
Inspection agreed before ordering
Inspection items are agreed with each order: boundary dimensions, running accuracy, starting and running torque, appearance and sealing, and batch traceability. The approved drawing and the agreed items define the supplied bearing.
Harmonic reducer bearings and flexible bearings
Crossed roller bearings with bolt holes in both rings serve as the output bearing of harmonic reducers. See SF and HF harmonic reducer output bearings. The thin ball bearing on the wave generator cam is a different product with its own selection rules. See PRZ flexible bearings.
Frequently asked questions
Does NLHB supply crossed roller bearings?
Yes. NLHB provides supply and customization support for the RAU thin-section crossed roller bearings in the table and for SF and HF harmonic reducer output bearings. Send the model or drawing with your operating conditions.
What does the UU suffix mean?
UU marks the sealed version. In the RAU table the 8 mm and 13 mm wide sizes are listed as UU. Seal type and material are confirmed for each order.
Can I order a size that is not in the table?
Send the drawing. Bore, outside diameter, width, mounting holes and seals are reviewed against your design before quoting.
Are the load ratings guaranteed values?
They are catalog ratings for initial selection. The supplied bearing is defined by the approved drawing and the inspection items agreed with the order.
Can you meet a running torque or preload requirement?
State the target starting or running torque and the clearance or preload in your inquiry. These requirements are reviewed and agreed before quotation, then checked as agreed.
Do the photos show every model?
They show the series form. Dimensions and details of each size follow its drawing.
