Crossed Cylindrical Roller Bearings

[Intermesher]

Does anyone know of a source for Crossed Cylindrical Roller Bearings. They are shown in the SKF General Catalogue, but they say that they are not manufacturing them.

Any additional information on these bearing will also be of value.

Thanks

 

[diamondjim]

Rotek Inc. 330-562-4000 makes cross roller bearings.
Timken Co. in Canton Ohio makes tapered cross roller bearings.

 

[Intermesher]

dimondjim

Thanks for the two possible sources. It appears that they do not manufacture cylindrical crossed roller bearings. There is a NASA article

http://www.nasatech.com/Briefs/Jun02/NPO30203.html,

which suggests that these bearings should have crowned races to reduce scuffing. Maybe this is why SKF is no longer suppling them.

Does anyone have additional information?

 

[diamondjim]

I worked for both companies and they both make
cross roller bearings. I just retired from Rotek
and we have made many for tunnel boring application.
They were not crowned rollers but crown relieved rollers.
For continuous duty or high speeds a cage is needed in
the design. For slower applications plastic spacers
are used and if very slow no spacers or cage is used
maximizing the static capacity of these. Some of the
cross roller disigns have had 2 rollers in the thrust
direction and then 1 roller in the opposing direction
installed around the bearing. I have seen 3 roller to
1 also in catalogues. Rotek makes large bearings that
bolt on to stuctures. Most of the cross roller designs
have been changed to the 3 roller design if space permits.
Harvey Sable or Mark Gonczy from Rotek should be able
to help you. You may tell them that Jim Geisey referred
you to them. If you are talking about small bearings ie
under 12 inch diameters, Rotek does not make that product
line. Feel free to call me at home as well. 330 678 0226.

Timken makes tapered cross roller designs and most of
their rollers are crowned as far as I know. Who did you
talk to about these? I think crown relieved may be
an alternative to full crown.

From the article that you suggest, are your talking
about polymer rather than steel. If so you are correct.
Neither Timken or Rotek make plastic bearings. What is
your application?

I think SKF was sued many years ago and dropped that
product line. These were bolt on bearings that replaced
ball bearings. Cross roller bearing demand very rigid
mountings and very flat surfaces to ensure full load
support.

 

[Intermesher]

dimondjim,

Thanks for the informative post.

The application is aerospace, the intent is to use steel bearings, the outside diameter will be approximately 7 inches and the speeds will be approximately 500 and 700 RPM.

The specific application is for the rotor hub on a light helicopter. Unlike conventional helicopters, this rotor must be very rigid. There is therefor the need for light weight and yet be able to handle large moments.

 

[diamondjim]

Intermesher,
I do not know to whom you spoke but both
companies make cross roller bearings.
Rotek rollers are crowned relieved to reduce
the end stresses. I think Timken still puts
a full crown on the tapered rollers but am not
certain about the tapered cross rollers.
If you mean that niether make polymeric bearings,
you are correct. Rotek just finished a large
tapered xr bearing inner and outer races for a large
cross roller bearing for Timken. Rotek does not
make tiny bearing ie under 12 inches. Plastic has so
little load carrying ability, that we never seriously
considered these for any heavy duty application.
As to crowning the raceways, it would be very
difficult to gage or machine these, fine turning
might be an option.

 

[AHRBearing]

Can you advise on the magnitude of the moments? I've had experience on helicopter bearing design and I can appreciate what your after. I know of a company in Germany that could do it but it would depend on the loads and the target unit weight your after.

AHR International Ltd

http://www.ahrinternational.com

 

[Intermesher]

AHRBearing

The desired bearing appears to be the SKF MMXC 1926. The dimensions are ~ ID = 130 mm, the OD = 180 mm, and the width = 24 mm. The basic load ratings are ~ Dynamic = 61,600 N, and Static = 100,000 N. The weight is 2.15 kg.

 

[AHRBearing]

With the MMXC1926 now no longer available can you advise on the following?
1) Is your present design fixed to the dimensions of the SKF MMXC1926 bearing? Can you accept a small change in bearing OD for example? (Mass may change marginally here).
2) What time scale do you require this in?

regards

Neville

AHR International Ltd

http://www.ahrinternational.com

 

[Intermesher]

AHRBearing

The following is in response to your questions.
1) Neither the specific bearing nor the dimensions are fixed. This project is in the design stage.
2) The initial bearings are for the prototype and their delivery time should be less than 6 months.

Thanks.