shaft bearing position calculation

[nyvens]

hi!

i have a shaft coupled with a motor, via a spider coupling.
The shaft length is yet to be detemined (will be < 150mm) and its end is fitted in a bearing for support. (Shaft diameter:25mm)

I was wondering if one bearing will be sufficient to support the shaft. How can i calculate that?

If one bearing is used, can the spider coupling act as support for the shaft, or is it better to use 2 bearings.

your help is most welcome.

 

[hydtools]

Do not depend on the coupling alone for shaft support. Add a bearing.

Ted

 

[eromlignod]

You have to have a bearing. The spider coupling will just fly to pieces.

Don
Kansas City

 

[handleman]

No, the spider coupling can't act as support. The purpose of the spider coupling is to "give" just a tiny, tiny bit to compensate for misalignment between the shaft and the motor. Whether or not the bearing is sufficient depends on the bearing, but I would say probably not. Most shaft bearings are not intended to support a moment.

-handleman, CSWP (The new, easy test)

 

[MotorVib]

eromlignod is right it would not work. If you are looking in to something like that take a look engine flywheels. For MG sets from about 10Kw to about 3 Mw the generator counts on the engine rear brg to support the rotor wt.

Chris

"In this house, we obey the laws of thermodynamics." Homer Simpson

 

[dvd]

I agree that the spider coupling is a bad choice. You might consider a chain coupling. It really depends on how much use your machine will get.

Two bearings is preferred, but I have supported shafts off of component bearings on numerous occasions. Just do your homework to make sure the motor bearing can handle the overhung load from all the resolved forces, not just the shaft and coupling weight..

 

[handleman]

If you really insist on using the motor shaft to support the weight, I would recommend a solid, completely rigid coupling and a self-aligning bearing on the other end. As I said before, any coupling other than a rigid one is intended to flex/give to make up for misalignment between the rigidly mounted driven shaft and the motor shaft. If you rely on a chain coupling, spider coupling, helical machined coupling, or any other type of flexible coupling to support weight your shaft will vibrate, your coupling will wear out, or your bearings will wear out.

-handleman, CSWP (The new, easy test)