Nonmetallic wheel bearings

[DvonG]

Greetings, fellow engineers!
I am seeking advice for our application, which is a completely nonmetallic wagon carrying an electromagnetic transmitter/receiver system. The current wheel bearing assembly has failed. It consists of zirconia-toughened alumina (AZT) bushings (~ 4" long, inserted into the wheel rims) with a carbon-fiber-reinforced-polymer shaft (a thin-walled, 1" O.D. tube) as a fixed axle. Failure occurred when the bushing abraded the shaft enough to seize, causing the shaft to rotate and to break free of the restraints on the wheel housing. A field repair (cleaning and reassembly with liberal amounts of white lithium grease) lasted two days, until the shaft itself broke in two. The load on the wheel ~60 lb, nominal service speed ~1 rev/sec, short-term max. speed ~4 rev/sec. Any ideas (especially using other materials with the same bushing-bearing design approach) would be greatly appreciated.

 

[MikeHalloran]

Make the bushings from wood. Or use traditional laminated wood oxcart wheels. Use lots of grease, and don't expect miracles wrt lifetime.



Mike Halloran
Pembroke Pines, FL, USA

 

[unclesyd]

Bearings as per the suggested by mikeHalloran

http://www.woodexbearing.com/

 

[DvonG]

Thank you, MikeHalloran and unclesyd, for your quick replies. The woodexbearing.com web-site has hardwood bushings we can use.
Any suggestions for the non-rotating axle, which has to be 18 inches long and completely nonmetallic?

 

[unclesyd]

What size is require ,dia and length ?

What type of loads?

 

[DvonG]

Wheel bushing is zircon-toughened alumina, 4 inches in length.
The shaft has to be 1 inch O.D. and 18 inches long. The bearing (journal) surface is 4 inches. The shaft supports TWO wheels (side-by-side). A 4 inch long cylindrical spacer separates the bushings. The load on each wheel is 60 lb (120 lb total load on the shaft). Wheel rotation: 60 RPM steady operation; 180 RPM in short (10 sec) intervals.

 

[unclesyd]

Here are few suggestions for your shaft. You will have to take a look at your application to see which one is best suited. I tend to favor the Micarta as I've used it in many applications as both a bushing and shaft.
I would give each reference a call and discuss your problem, especially Norplx-Micarta as they have been extremely helpful in the past.

Carbon fiber the ultimate material.

http://www.bactechnologies.com/index.html

All the glass reinforced materials along with extruded unfilled material.plain.

http://www.calsakplastics.com/display_category_products.php?C

ategoryID=745

High strength:

http://www.norplex-micarta.com/products/29/TDB NP511B.pdf

Internal lubricant:

http://www.norplex-micarta.com/products/68/RM315_TDB.pdf

 

[diskullman]

Plastic bearings with glass balls

http://www.jilson.com/radial.htm

Russell Giuliano

 

[DvonG]

Hi, diskullman.
Early on, we tried plastic bearings (delrin with glass balls). Unfortunately, they failed when the balls shattered. I will check the website you posted...perhaps we can revisit this.

 

[sreid]

Torlon Ball Bearings?

http://www.professionalplastics.com/TORLONBALLS