New type of bearing?
New type of bearing?
(OP)
Has anyone like me felt the need of a new type of ball/roller - bearing with an integrated sealing. Very often when designing some type of gearbox or other casing with a shaft coming out of it, one needs a sealing to keep the oil on the inside. To do this with a separate sealing makes the design bigger and more clumsy. It also makes it more expensive to manufacture. When it's time for repair it is easy to change the bearing but sometimes the sealing has wearn in to the shaft witch then needs to be exchanged or repaired. Wouldn't it be great with a ballbearing with an integrated sealing that seals between the inner and outer rings in the bearing? I understand that it needs to be fitted either over a o-ring or with some kind of glue or silicone to prevent leakage between the shaft and the inner ring as well as between the housing and the outer ring. It still would be a more effective design and it would be possible to use it in a lot of applications.
When I have asked people working for SKF, FAG or INA aboute this I have got what I think a very stupid answer: "We don't do it because no one asks for it." Ofcause no one asks for it since there isn't any such bearing.
WHAT DO YOU THINK?
Leffe
When I have asked people working for SKF, FAG or INA aboute this I have got what I think a very stupid answer: "We don't do it because no one asks for it." Ofcause no one asks for it since there isn't any such bearing.
WHAT DO YOU THINK?
Leffe





RE: New type of bearing?
Cyril Guichard
Mechanical Engineer
RE: New type of bearing?
I have seen this type of design on large
tunnel boring equipment and also some
mooring buoy equipment. The seals were
very large and special welding technique
was applied to the wear surface to allow
a very hard rubbing surface and then
ground. It was expensive and the running
torques were out of sight, but the customers
had plenty of drive to overcome this.
To effectively seal out oil the lip pressure
of the seals must be very high. I have
seen a seal act as a pump and actually pump
the oil out of the bearing. I do not know if
it was because of excess axial play or not.
Most bearing manufacturer do not make these
exotic seals and expect seal manufacturers
to come up with suitable designs. Often they
are spring loaded and difficult to assure the
accuracy required to effectively seal out oil.
If you have enough money and insist that these
be incorporated into the design and can assure
enough sales volume to warrant the production costs
and assembly problems, I think any bearing
manufacturer would help you. The cost of developing
a prototype can be extremely high and then may
not effectively seal out the oil depending on
clearances and runout of the seal with respect
to the raceway system and accuracy of the installation
at your sight. Also the disadvantage is that if
it does leak, you have to replace the whole assembly
instead of only the seal. Yes, it can be done.
RE: New type of bearing?
RE: New type of bearing?
So what I want to compare with is not a ballbearing but a ballbearing and a sealing. Compared to a traditional design this shaft can be machined to a rugher surface, (cheaper)the sealing runs against a smother hardened surface (no leak) (less wear)(longer lifetime)(less friction)and when I change the bearing I also have the sealing and the surface it is running against, changed without problems with the sealing has worn in to the shaft.
Leffe
RE: New type of bearing?
The only difference I can see is that the lip seal in yours is physically bigger (more reliable?), and so yours is longer. I have used sealed ball bearings with a seal on only one side to retain oil in gearboxes - worked fine. Yours could work better - but unless you have a problem when using a sealed bearing, why bother? Have you tried a standard sealed ball bearing ?
RE: New type of bearing?
RE: New type of bearing?
RE: New type of bearing?
Leffe
RE: New type of bearing?
1. The only part of a lip seal that actually does anything is the tiny area that contacts the shaft, so just because your proposal "looks" more reliable does not necessarily make it so - although it may very well be.
2. If you are saying that the advantage of your proposal is "customer perception", I can't argue with you, but its not an engineering issue.
3. Have you ever tested a single sealed bearing?
RE: New type of bearing?
RE: New type of bearing?
The same seal is/could be applied to specially made ball bearings, but they are generally wider than normal beairngs.
This would improve sealing, but your friction levels would increase.
On some big gearboxes we used a lbayrinth seal similar to that found in a standard SNU bearing housing. There was a bit of machine work involved, but it worled extremeluy wel in reality.
Hope this helps!
Lester Milton
NBC Group Ltd, Telford, Shropshire, UK
RE: New type of bearing?
Is what's shown actually been assembled? I can't see how you can get the balls into the race groove.
TTFN
RE: New type of bearing?
If you're going to get really picky, there doesn't even seem to be a cage - it looks like it's full complement, so without a split inner race it would be unassemblable whatever the groove depth was. I expect its just for illustration purposes.
RE: New type of bearing?
Leffe
RE: New type of bearing?
RE: New type of bearing?
RE: New type of bearing?
- the generalities built into bearing usage. A floating race would be difficult to seal, yet is common. Allowable temperatures for heat fits would compromise seal materials.
- One of reasons that modern day bearings are so successfull is their compactness.
- A box flush would be hard considering that the flush mediums require seal changes.
- throughbox shafting is typically designed to avoid flooding of bearings, avoiding lub pressure issues.
- increased maintenance expenses without any real advantages would move a manufacturers box down on the desirability list.
- If your sprung a seal leak with your design, and you told your manager that the box needs to come apart for a bearing replacement because of an oil leak, you still might be subject to job loss.
- if no one else has asked for such a configuration, you will likely bear the entire cost of manufacturer/supply. You will loose your job.
RE: New type of bearing?
Be fair to this guy - if its a standard seal incorporated into this bearing, and its accessible from the outside, you don't necessarily have to replace the whole bearing or disassemble everything if the seal itself fails. And a standard seal that fails because of shaft wear would be much more expensive to fix than just replacing the bearing - unless you maybe use a speedi-sleeve.
RE: New type of bearing?
My experience has shown that erosion of the seal face on shafting is almost always accompanied by erosion of the bearing seat. In fact the latter brings on the preceeding. Unless of course mechanical damage has taken place. Bearing failure will typically not destroy seal faces unless it is catastrophic, or is allowed to continue to the point that bearing seats are damaged, which will almost always lead to seal face damage. Worn seal surfaces on shafting are an indicator of other problems. Incorporating the seal into the bearing does nothing to address those problems.
RE: New type of bearing?
RE: New type of bearing?
RE: New type of bearing?
RE: New type of bearing?
Leffe
RE: New type of bearing?
RE: New type of bearing?
Yes - it may look familiar, but it will not be identical !. For one thing, with Leffe's design there will be fewer precision diameters present (either one less or two less). And secondly, with Leffes design there will a seal running on through-hardened 62100 bearing steel - you can't do much better than that for seal reliability. From a designers point of view, it has merit. The big problem is getting initial acceptance and making it a de-facto standard. Until that happens, (if it ever could happen), there will a long period where such bearings are only available from one vendor, and nobody knows about them etc, and people can't get spares etc etc. But I have noticed a trend towards these combined components -especially in automotive. Take INA for instance - they seem to be making a lot of "combined" products. And I would never have believed that you would ever want to integrate ball bearings and front axle housings into one throw away part - but they do it now. Of course, I realize that automotive "consumers" are the same thing as industrial customers!
RE: New type of bearing?
RE: New type of bearing?
RE: New type of bearing?
RE: New type of bearing?
I can easily see the potential use and practicality of such a bearing/seal combination. Not only does it allow for ease of installation, but cuts costs in many ways. No special materials or machining practices need be employed to utilize such bearings. Why not utilize the hard, ground surfaces of the bearing itself, as the seal surface? Isn't this cheaper than requiring the bearing seat material to be of such quality? With this in mind, yes, I can see the benefits of such a bearing.
When a typcial shaft seal is replaced, it is very common that not only is the seal bad, but also the metal frame that holds the seal. This is due to the forces and techniques of seal removal. So, in effect, two items are damaged, the seal material as well as the seal housing.
If the bearing itself is the seal housing, it is safe to assume that the simple removal of the bearing is all that is required to replace the seal material. Insert a new seal into the bearing housing, then simply reinstall the bearing. I am highly confident that the seal material itself, is less costly to replace, than the old method of changing the seal material along with the damaged seal housing.
I have seen a great deal of trauma to the gearbox, where the old seals are removed. The tools needed to remove such older seals, are indeed damaging to the gearbox itself. With Leffe's idea, there would be no damage to the gearbox or shaft, as well as the potential to keep the original bearing. Simply replace the seal in the bearing.
Let's face it, utilizing the exotic materials of the bearing itself, lessens costs of specialized materials and machining of the shaft and the gearbox material. Don't these savings in themselves, warrant further investigation into his bearing idea? Honestly, one cannot beat the hardness and sealing capacity of the bearing material itself.
As for getting people to accept the idea: When the telephone was invented, people thought it was a wondeful device, but nobody believed it would ever catch on, because they didn't believe that anyone would have so much to say to each other to warrant the purchase of a phone. Is this the initial stupidity of man when faced with something new?
I see two products here. One is a resealable bearing and the other is the seal the bearing uses. As it is now, if I use a sealed bearing, and the seal fails, I have to purchase a whole new bearing. I personaly would rather keep my good bearing, and just replace its seal for a fraction of the cost. On top of that, I would praise the ability to save tremendous costs in machining and materials of the machine itself that the bearings go into. Wouldn't any of you?
Good job Leffe, I am curious to see where this goes.