Bought these off Ebay purely for the price, there is a heap going for around $20. I was interested to know if anyone had any experience with them or knew anything about them? They've got an extended inner ring like Biltins and rubber seals (i think biltins are rubber sealed), really i just wanna know how long they last and if they clean well/easily?
There is some pretty detailed reviews on the manufactures website but any first hand opinions would be muy apreciado
http://www.vxb.com/page/bearings/PROD/SkateboardBearings/Kit8786
International -
http://stores.ebay.com/VXB-Bearings-Skateboard-and-Slotcar?_trksid=... - Thats the ebay store
DA BEAR said:
Were they from aussie ebay or international ebay?
I use them in my wheel sets as alternatives to biltins....
an extract from the smb technical data website...
CERAMICS (prefix "CB"hybrid or "CC" all-ceramic)Zirconia (suffix "ZrO2")
• Good corrosion resistance to cold water and many chemicals
• Good high temperature performance up to 400C without cage
• Non magnetic and electrically insualting
• Lower speed and load than steel bearings
• Not suitable for low noise applications
• Higher fracture toughness than other ceramics so better for small shock loads
• Expansion similar to steel so not a problem to use with steel shaft at high temperature.
Silicon Nitride (suffix "Si3N4")
• Very good corrosion resistance to water, salt water and most chemicals.
• Good high temperature performance up to 1000C without cage
• Non magnetic and electrically insulating
• Lower speed and load than steel bearings but Si3N4 balls are used in high speed hybrid bearings.
• Not suitable for low noise applications
• Much lighter than steel or Zirconia
• Very low expansion at high temperature.
Silicon Carbide (suffix "SiC")
• Best corrosion resistance of the ceramics.
• Best high temperature performance up to 1600C without cage
• Non magnetic
• Electrically conductive
• Much lighter than steel or Zirconia
• Very low expansion at high temperature.
Bearings can be supplied with steel rings and ceramic balls (hybrid) or "all ceramic" bearings with ceramic rings and balls. These all-ceramic bearings may have steel, nylon, PTFE or PEEK retainers or be supplied as full complement type. There are many advantages to ceramic materials such as a lower friction coefficient, much greater hardness and temperature resistance.
Hybrid Bearings have steel rings and ceramic balls. Silicon nitride is the most popular for the balls as it has only 40 percent of the density of bearing steel but is much harder giving greater wear resistance. Zirconia is heavier with 75 percent of the density of steel so is less suitable for hybrid bearings.. Hybrid bearings are also capable of higher speeds. Sometimes, excessive claims are made about the high speed capabilities of hybrid bearings. They can run faster than all steel bearings due to the lower centrifugal force generated by the ceramic balls but this is partially counteracted by the lower elasticity of the balls. As the balls are harder, the contact area between the balls and the raceway is smaller which causes a higher contact pressure. Under load, this can cause the raceways to wear faster than they would with steel balls. The speed increase for hybrid bearings is approximately 30 percent with adequate lubrication. Hybrid bearings can also operate better with limited lubrication as the lower friction material generates less heat but running speed should be reduced. Hybrid bearings are also less subject to ball skidding under inital acceleration due to the lower ball density.
All-ceramic bearings have good to excellent corrosion resistance, are non-magnetic and, apart from silicon carbide, are electrically insulating. All-ceramic bearings can be used in high to very high temperatures if supplied without a cage (full complement).
Electrical resistance: Si3N4 best, then ZrO2, then SIC which is conductive.
High temp resistance: SiC best (1600C), then Si3N4 (1000C), then ZrO2 (400C)
Corrosion resistance: SIC (excellent), then Si3N4 (very good) and ZrO2 (good)
Load capacity: SIC highest then Si3N4, then ZrO2
Fracture toughness: ZrO2 best, then Si3N4, then SiC
All-ceramic bearings have lower load and speed ratings than steel or hybrid bearings. The speeds are lower due to the lower precision and roundness of the rings and the loads are lower because the material is more brittle. Under heavy loads and particularly heavy shock loads, there is a risk of cracking. For the same reason, great care should be taken with interference fits. Zirconia is the least brittle so it will handle shock loads and very small interference fits better than the other ceramic materials with silicon carbide being the most brittle. Shock loads should be avoided with all-ceramic bearings. Great care should be taken when using ceramic bearings (especially silicon nitride and silicon carbide) on steel shafts at high temperature due to the difference in expansion coefficient and the relative brittleness of ceramics. For more information see Shaft/Housing Fit
WARNING: Customers often expect very low frictional torque with low noise and vibration levels from hybrid bearings. This may be possible but the bearing rings must have very good roundness and a high quality raceway finish while the balls must also have very good roundness and surface finish. A hybrid bearing with poor roundness and raceway finish will have much higher friction levels, higher vibration and a lower maximum speed than a good quality all-steel bearing. Drag in a hybrid bearing can be reduced by reducing lubrication or running the bearing without lubrication and there are greater possibilities with hybrids than with conventional steel ball bearings but noise and vibration levels will still be high unless the roundness and surface finishes are of a high standard.
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