Bearing support for vertical shaft?

[cdods]

I have short (12") vertical shaft. The shaft will supported at the top and bottom by a bearing. The only axial load will be from the weight of the shaft and gears on the shaft. I'll estimate the total weight of the shaft and gears at around 5 lbs. Shaft will rotate at around 1000 RPM.

From a practical standpoint, do you think I can get away with a standard roller or ball bearing for the bottom bearing, or do I need a bearing design to handle axial load? If so, any suggestions what the cheapest kind of bearing that would work for the bottom bearing?

 

[Fluxion]

I would think you would be fine. I'm not an expert but I recently put bearings in a wood shaper of mine with a 1-1/4" spindle and it took your run of the mill sealed bearing. The shaft weighed at least 5 pounds and some of the shaper heads I have weigh that much or more.

 

[larry_g]

Straight cut of bevel gears? Bevel gears have a thrust component to them and will have to be held in position to work correctly. Most radial bearings will have a thrust specification. Without knowing more about your system it is hard to say what you might need to make things work correctly.

You may want to research Angular contact ball bearings. They come in different ratios of radial/thrust load.

lg
no neat sig line

 

[Advan]

A standard deep-groove ball bearing is designed to take some axial loading. Although you haven't mentioned size, 5 lbs isn't much, so I think it would work for you.

 

[waynem]

Assuming you are using mounted bearings, get the cam lock type. They grip the shaft a lot better than the set screw ones. Used them on a machine we manufactured with a vertical 1" spindle that took a lot of axial abuse and they worked great.

 

[theoldwizard1]

From a practical standpoint, do you think I can get away with a standard (plain) roller or ball bearing for the bottom bearing, or do I need a bearing design to handle axial load?

Those bearing provide no axially load capability at all. While not designed to provide axial load, a standard tapered roller bearing (like from a trailer wheel bearing) would likely work if kept well lubed. Of course this means that the shaft must be machined to accept the inner race and not let it slide up the shaft. What speed and what duty cycle ?

Top bearing can be a plain roller or ball bearing.

Bigger is better, even if you have to weld something on to the shaft and then machine it.

For heavy loads, you would need a turntable/slewing bearing. Neither of these are well suited for high speed.

 

[bullnerd]

There are deep groove bearings that have a side load rating. Look like standard bearings.

Mcmaster carr has them.

 

[Spacey_G]

Needle roller bearings cannot take axial loads, so you'll want to avoid those. Tapered roller bearings are designed to take axial loads and do so quite well. A normal deep groove ball bearing can take some axial load and sounds like the best option here.

Take a look at the reading material published by the various bearing manufactures, e.g. SKF. They do a good job with this type of application info. Alternatively you could look in a machine design text.

 

[nbpt100]

There are deep groove bearings that have a side load rating. Look like standard bearings.

Mcmaster carr has them.

Needle roller bearings cannot take axial loads, so you'll want to avoid those. Tapered roller bearings are designed to take axial loads and do so quite well. A normal deep groove ball bearing can take some axial load and sounds like the best option here.

Take a look at the reading material published by the various bearing manufactures, e.g. SKF. They do a good job with this type of application info. Alternatively you could look in a machine design text.

Well said.


Who ever bearings you use should have loading specs for both radial and axial applications. Consider the force component from the bevel gears, as suggested earlier.

Get the cam lock as suggested above. If you can't you can use a single piece shaft collar and use that on the top and bottom to fix the shaft to the bearing.
If you use the set screw type of bearngs put a flat on the shaft or better yet spot face it and use a dog point set screw.
If you are using mounted bearings you should use self aligning. the Spherical outer race.....

It does not sound like a very demanding application but there is still stuff we don't know about it. Good Luck!

 

[theoldwizard1]

about a million years, I worked on a student team developing a vertical turbine. We used a tapered truck front axle bearing. Once the shaft was aligned to true vertical, it spun very easily. It was a lot more than 5 lbs of load axially on that bearing.

The ultimate bearing would be a magnetic bearing to carry the vertical load and light roller/ball bearings at top and bottom to keep it aligned.

 

[cdods]

Thanks everyone, I didn't realize all bearings had a thrust spec, it sounds like a deep roller bearing is the way to go. The plan was already to use a bearing with locking collar. I have great local bearing place that will provide good advice, I just wanted to have an idea of what I'd be looking for before I go talk to them.

I specifically didn't mention the application as I figured more the of the advice would focus the application than the bearings. But in case you're interested, the application is a DIY go kart. We bought a cheap lawn tractor and are using as much as we can from than as a father / son project building a go kart. That means that I'm dealing with a vertical shaft engine, and a transaxle that also has vertical input. The shaft in question will act as a intermediary shaft between the engine and transaxle. I mis-spoke when I said gears, what I should have said was sprockets. The shaft in question will take power from the engine via a belt driven pulley, then connect the transaxle via sprockets / chain.

I know this is far from ideal which is why I didn't go into detail, but it's what works with what we have.

 

[nbpt100]

Good Luck......and have fun! You do the best you can with what you got! I totally get that! The experience and learning process is more important than the actual outcome.

 

[ttpete]

Those bearing provide no axially load capability at all. While not designed to provide axial load, a standard tapered roller bearing (like from a trailer wheel bearing) would likely work if kept well lubed. Of course this means that the shaft must be machined to accept the inner race and not let it slide up the shaft. What speed and what duty cycle ?

Top bearing can be a plain roller or ball bearing.

Bigger is better, even if you have to weld something on to the shaft and then machine it.

For heavy loads, you would need a turntable/slewing bearing. Neither of these are well suited for high speed.

My Ducati motorcycle uses a 6202 radial rated sealed bearing as a clutch release bearing. It has several hundred lbs. axial load on it when it's holding the clutch released for several minutes waiting for a traffic light. It's been doing it for seven years now without a problem. If the axial load was for hours at a time, it might be advisable to go to two 7202 series angular contact bearings placed back to back.