thrust bearings
mark
I would also like to have a thrust bearing because the shaft will have
a load from one end. I assume this is not good for the pillow block
bearings. How do I go about this. Can you buy off the shelf thrust
bearing assemblies the way pillow block bearings are sold? Thanks
Winston
Sounds like a job for opposed angled roller bearings:
http://www.mcmaster.com/#ball-and-roller-bearings/=5d7yfq
--Winston
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Ned Simmons
wrote:
Normal ball bearing pillow block bearings can carry thrust loads. If
the thrust is less than 20% of the dynamic load rating of the bearing
you probably don't have to worry. If it's more than that you should go
thru the procedure in the bearing mfr's catalog to calculate the
equivalent load using your anticipated radial and thrust loads.
You can get tapered roller bearing pillow blocks, but they're larger
and much more expensive.
When applying thrust loads to a pillow block you do need to consider
the strength of the housing, its mounting, and the means for
transferring the thrust between the shaft and bearing.
How much load, radial and thrust, are we talking about?
--
Ned Simmons
Larry Jaques
<mark...@hotmail.com> scrawled the following:
Is this loading perpendicular to the shaft? If so, the standard ball
bearings in the pillow blocks should handle it easily, if loads are
within their normal range.
Non-perpendicular loads would require different bearings, maybe
tapered rollers like a wheel bearing setup.
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of passing through hard times bravely and cheerfully.
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mark
wrote:
> On Wed, 13 Jan 2010 18:42:34 -0800 (PST), the infamous mark
I am building an airboat, the prop shaft will be above the engine
driven by belts. I was planning on using a 2' long 1.5" shaft
supported by 2 1.5" pillow block bearings and then making a hub to
mount the prop to on the end of the shaft. The side load of the
bearings would come from the prop pushing the shaft. I priced the
tapered roller pillow block bearings and they are $350.00 each, not an
option. The other idea I thought of was using a 1 piece rear axleshaft
from a pick-up as the prop shaft. Make an adapter for the prop to
hubface and the tapered rollerbearing on the other side should take
the load. Mount the shaft with 2 pillow block bearings. The boat will
weigh about 1500lbs and we are using a stock chev 350 at 2500-3000rpm
max.
mark
> On Wed, 13 Jan 2010 18:42:34 -0800 (PST), mark <markha...@hotmail.com>
I did some checking and it seems the HC208-24 bearing that these
pillow blocks use have a dynamic C load rating of 30000 (N) and a
static Co load rating of 20000 (N). What does this mean?
Ned Simmons
wrote:
>On Jan 14, 12:37�pm, Ned Simmons <n...@nedsim.com> wrote:
C is the load that 90% of the bearings in a sample will support for 1
million revolutions before failure. Life and load are linked by an
inverse 3rd power relation. In other words, if you reduce the load by
half, the life will increase 8 times. (2x2x2=8)
Co is the load that will permanently deform the bearing some very
small amount. I don't remember the amount off the top of my head.
30000N equals 6700 pounds force.
--
Ned Simmons
Wild_Bill
see some pictures of the project.
Thrust bearings can be bought as an assembly, but I've never had a need to
find any in the sizes you're needing, so I can't recommend a source.
A bearing distributor should be able to help with some recommendations,
check your yellow pages to see if there are bearing distributors in your
area.
Applied Industrial Technologies is a nationwide USA vendor, which I go to
locally.
http://www.applied.com/site.cfm/bearings_new.cfm
There is a Locate Service Centers link at the top of the webpage
--
WB
.........
metalworking projects
www.kwagmire.com/metal_proj.html
"mark" <mark...@hotmail.com> wrote in message
news:f2db428d-2944-43fb...@q41g2000vba.googlegroups.com...
mark
> On Thu, 14 Jan 2010 19:03:03 -0800 (PST), mark <markha...@hotmail.com>
>
> - Show quoted text -
So if they will handle 6700 lbs of force each then 20% of that as
somone above mentioned is acceptable for side load come in at at 2600
lbs side load. That should be fine and I could install a 3rd one for
extra strength.
newshound
> I am building an airboat, the prop shaft will be above the engine
> driven by belts. I was planning on using a 2' long 1.5" shaft
> supported by 2 1.5" pillow block bearings and then making a hub to
> mount the prop to on the end of the shaft. The side load of the
> bearings would come from the prop pushing the shaft. I priced the
> tapered roller pillow block bearings and they are $350.00 each, not an
> option. The other idea I thought of was using a 1 piece rear axleshaft
> from a pick-up as the prop shaft. Make an adapter for the prop to
> hubface and the tapered rollerbearing on the other side should take
> the load. Mount the shaft with 2 pillow block bearings. The boat will
> weigh about 1500lbs and we are using a stock chev 350 at 2500-3000rpm
> max.
OK so you will have way more thrust load than pillow blocks normally see,
but maybe comparable to truck cornering forces, so I like the idea of
adapting an axleshaft. But, cornering forces are only intermittent. So I
think it might be worth doing some simple design sums. Do you have a prop in
mind; if so, presumably you can find out the thrust force at typical revs?
Even if you don't have bearing catalogues to hand, post the load and speed
here, and someone will help you size your thrust bearing for a given service
life.
dca...@krl.org
Take a look at the W.W. Grainger catalog. Not because it has the best
selection of bearings. But because they only stock tapered roller
bearings that in common use. And the bearings in common use are less
expensive. You might note that they stock 1.375 inch bore, and 1.750
inch bore , but no 1.5 inch bore roller bearings.
Dan
Ned Simmons
wrote:
>
>So if they will handle 6700 lbs of force each then 20% of that as
>somone above mentioned is acceptable for side load come in at at 2600
>lbs side load. That should be fine and I could install a 3rd one for
>extra strength.
I threw out the 20% figure as a quick and dirty place to start. It's
more complicated than that and, now that I see this project involves
large objects swinging at high speeds near your head <g>, I'd urge you
to go thru the bearing manufacturer's procedure to calculate the
equivalent load for a combined axial and radial load. Once you have
the equivalent load you can figure the bearing's predicted life.
Do *not* assume that the axial load will be shared by the bearings. Do
the calculations assuming that one bearing will carry all the thrust.
--
Ned Simmons
mark
the shaft (opposite end that the prop is on) from 1.5 to 1.125 and
just a bit less than the thickness of a shielded integrated steel ball
thrust bearing
(mcmaster part # 60715K16) rated at 7000 lbs thrust load. This will be
pushing on part of the framework and I was thinking of "bedding the
end of the bearing with JB weld or something similar so it will be
evenly seated.