Can a gearbox output shaft be made thin with this design?

[a61098417]

TL;DR

The output shaft of the gearbox undergoes torque and bending force(tensile force of the belt)(I use belt after gearbox). If I mount/fix the pulley on other things instead of the output shaft, the belt won't bend the shaft. Thus, the output shaft gets torque only. Is my design correct?

Is this design correct?

 

[berkeman]

Welcome to PhysicsForums. Can you post a drawing or picture of your arrangement, and comment on what kind of bearings you are using at each joint? You can use the "Attach files" link below the Edit window to upload PDF or JPEG files.

 

[Baluncore]

Is this design correct?

There are many solutions. There is no one correct design.

Where an additional bearing is provided, it must be positioned and aligned correctly, or it will not carry the required forces without increasing stresses in the shaft. Will you have a flexible coupling between the gearbox and the pulley shaft?

The problem with supporting the output shaft on both sides of the belt pulley is that you are restricted to a mounting that enables you to change the belts quickly, without special tools.

What does the belt drive? A compression strut, floating in spherical self-aligning bearings, between two shafts, can counter the belt tension, while making it possible to change the belt quickly.

Specify the power to be transmitted.
Specify the RPM of the output shaft.
Compute the torque in the shaft.
Specify the pulley diameter and the tension in the belt.

The minimum possible shaft diameter to consider must satisfy that torque requirement.
Now analyse the bending due to belt tension with one or two support pulleys.

 

[Lnewqban]

Another solution to a marginal output shaft diameter could be a coupling between it and an independent shaft, supported by two bearings, for the pulley, which could be mounted in a cantilever set for easy belt replacement.
Careful alignment should be performed for both shafts, in order to extend the life of the coupling.

Please, see:
https://sdp-si.com/Rivin/art1.php

https://www.ksb.com/centrifugal-pump-lexicon/shaft-coupling/191984/