Locking mechanism apart from worm gear

[waheed7]

Hey all,

I need to make a device to allow heavy flanges (25kg) to be rotated. the following is what I have come up with, but the lead engineer wants to get rid of the handle and just have hand movement of flange which is then somehow fixed. I can't see another way to do this, any help would be appreciated.

Waheed

 

[MikeHalloran]

I don't see a trace of a worm gear or a bevel gear in your sketch.
Why does the caption mention both?

You want to rotate the flange, not through its own axis, but through a diametral axis that goes through the center of gravity, right? I have to agree with your lead engineer; you shouldn't need a lot of torque to rotate the part, all you need is a spring-set brake. The rating of the brake you need is determined by what loads will be applied to the flange while it is fixed, e.g. how big a hole you want to drill in it, and how far the hole is from the fixture axis.



Mike Halloran
Pembroke Pines, FL, USA

 

[waheed7]

Thanks for your help Mike!

Got an intern to make the drawing and he couldn't get worm/bevel gears in there, so I just captioned it for the time being to explain where they were meant to be.

The flange to be worked on is going to be placed on the one shown, as in fixed onto it, so the axis of rotation doesn't pass through the whole center of gravity. But yes diametral axis.

And he wants it to be purely mechanical based as far as possible, I did ask him about any electric operated mechanism, but he wants unpowered. And surely worm gear would be cheaper option?

 

[MikeHalloran]

Worm gears, once assembled and mounted, are not particularly cheap.
Worse, for a fixture at least, they have some backlash, where they exert no resistance.

Even if you mis-assemble them intentionally or use split worms and such to remove the lash, they're rated in such a way that they're not very stiff as fixture brakes. ... unless you over size them, in which case they are definitely not cheap.

In your case, your boss is probably thinking of something like a ship's wheel to rotate the fixture, with a spring-set disc brake comprising a small caliper at a large radius, i.e., with the disc bolted to the wheel near the wheel rim.




Mike Halloran
Pembroke Pines, FL, USA

 

[Windward]

I am thinking of a split collar on the rotating shaft, clamped with a vise grip. Talk about cheap.

 

[waheed7]

@Mike Hmm em brakes definitely more suitable then, I'll try to convince him to go for it. I think it would be less hassle/time consuming/resources etc to just buy the brakes then design/custom make the wheel design. Thanks alot!

@Windward: i would definitely do that for my personal shop