Noob bearing question
2

Question

Noob bearing question

AlexPl81 (Mechanical)

(OP)

10 May 19 19:32

Hello,
i was hoping someone can help me with a bearing question. I'm currently building a tricycle, and i'm in a process of remaking the steering (old design had flaws). I have decided to try and use UCFL 204 bearing for the shaft (please see the picture, my apologies for my drawing skills). The top part of the shaft will have steering lever, and the bottom part of the shaft moves the plate, which is attached to front wheels with metal rods (its a tadpole trike, 2 wheels at the front) To my surprise the actual bearing is pretty loose in the casing. If i twist the shaft, the bearing moves in the case (despite me tightening the only screw on the casing). Is it normal for it to move under load? Can something be done, like welding the casing to the bearing, perhaps? I would rather not do any welding, as i'm building no-weld prototype. I'm thinking of using second bearing higher up on the shaft, as 1 bearing seems insufficient here, so perhaps that can help a bit, but i would appreciate any advice, as i have no experience with bearings. Thanks

https://files.engineering.com/getfile.aspx?folder=a873ad3c-a3f4-4c9d-a92b-a

electricpete (Electrical) · Answer 1 · 2019-05-13 16:14:21

Quote (Alex)
If i twist the shaft, the bearing moves in the case. Is it normal for it to move under load?

I googled UCFL, which led to...
https://www.astbearings.com/catalog.html?page=prod...

Then I pressed the link for general, which led to:
https://dpk3n3gg92jwt.cloudfront.net/domains/ast_u...

In that pdf, it states:

Quote (astbearings)
General Description
Mounted Bearing Units are designed to allow for the static mis-alignment of the bearing inside the housing because of the spherical shape of the outer diameter of the bearing insert and the concave shape of the inner diameter of the housing. This design allows the bearing unit to adjust for initial shaft mis-alignment which helps reduce abnormal bearing load. The allowable aligning angle of standard ball bearing units is 3º, while units with covers is 1º. Note, the Mounted Bearing Unit is not designed to swivel dynamically

So, the bearing is designed with spherical seat of the bearing and housing specifically to allow this type of rotation. It is normal for the particular type of mounted bearing that you bought. If you want the handlebars to be held at a predictable location and not wobble all over the place, then I think you want a different type.

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(2B)+(2B)' ?

AlexPl81 (Mechanical) · Answer 2 · 2019-05-14 18:11:51

Quote (electricpete)
So, the bearing is designed with spherical seat of the bearing and housing specifically to allow this type of rotation. It is normal for the particular type of mounted bearing that you bought. If you want the handlebars to be held at a predictable location and not wobble all over the place, then I think you want a different type.

Thank you so much! That has cleared things up a lot for me. I was searching for suitable solutions today and have found this one, UP003, Link
This is the best PDF could find for it (i probably just do not know where to look): Link
I cannot find a phrase " static mis-alignment" paired with these series anywhere on the web, so it gave me some hope.
I would really be grateful for your opinion on this one as well, if possible.

SwinnyGG (Mechanical) · Answer 3 · 2019-05-14 20:04:46

You really need to add a second bearing- the bearing types you're using are designed for normal loads only (i.e. perpendicular to the shaft that passes through the bearing) and not for moment.

A normal bicycle (or tricycle) steering arrangement has two bearings for this reason.

AlexPl81 (Mechanical) · Answer 4 · 2019-05-14 20:20:12

Quote (jgKRI)
You really need to add a second bearing- the bearing types you're using are designed for normal loads only (i.e. perpendicular to the shaft that passes through the bearing) and not for moment.

A normal bicycle (or tricycle) steering arrangement has two bearings for this reason.

Thank you! Once i have seen how single bearing works, i came to the same conclusion. I have added a second bearing last night, but have not tested the steering under load yet (I was mistakenly hoping that because this bearing feels so rugged (comparing to the tiny bearings in the normal steering column) - I can possibly get away with using one bearing only (and saving 0.5 kg on the second one). I also had them available at home as i bought them for the plastic shredder i'm trying to build (to work with 2.2 kw motor). Although I think the fact mentioned above (that it is quite flexible in the casing to allow for static misalignment) will not allow me to use them reliably in this setup even with the pair of them.

Michael-Lu (Mining) · Answer 5 · 2019-09-23 03:58:10

May be a problem with the clearance, have you considered it?

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Noob bearing question
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