OT Looking for a small Flanged UJ

[simonr]

I'm building a project (I'll describe it later) which needs to couple two components such that they are able to articulate left/right and up/down but not twist.

A Universal Joint is ideal - but I need one with flanges on either side which I can bolt to two flat plates. A bit like if you removed the drive flange from either end of a prop shaft and joined them with a single UJ.

Size wise, it needs to be bigger than the UJ's used in steering columns and smaller than used in Suzuki's (they are about 60mm diameter) - so I guess 30 to 50mm with the mounting flanges as close together as possible.

It must be free to articulate - so the rubber doughnut type CV's and anti vibration couplings are no good and it needs to achieve an offset of about 30 deg.

Sure I could make one - but it's a lot of hassle, particularly if I can find something off the shelf.

What's it for?

I'm building a 'pusher trailer' for a bike. Essentially an electric motor, batteries & controller built in to a small trailer which clips on to the back of a regular push-bike to propel it electrically. The trailer is single wheel - so needs to lean with the bike. As the bike leans, the trailer needs to articulate up & down as well as sideways.

The purpose of this is to test a couple of other ideas I have for the control system. They could equally be applied to any electric bike - but I like my bike as it is and don't want to install a 10kg motor to one of the wheels! With this, I just release one clip and I have my bike back!

Any ideas?

Si

[Big.Mike]

Misumi is always high quality, you just need to pick and play, there are flanges in there.:

http://uk.misumi-ec.com/eu/EcSearchView.html?kw=universal+joints&x=-1815&y=-28

Or what about a flexible drive shaft:

http://www.ondrives.com/p/14559/flf03020-04

Probably too expensive, you can build a flexible drive shaft from a stout flexible tube which is pinned through.

Cheers,

Mike

[David Sparkes]

You say the joint "needs to couple two components such that they are able to articulate left/right and up/down but not twist.".

I confess this confused me initially, as 'twist' is a mixture of up or down, coupled with simultaneous left or right.

Eventually I realised that by twist you meant 'rotate', as a drive shaft, steering shaft, etc. rotates.

You specify size parameters, but I'm not sure why 'such and such' is too small, perhaps it's to do with the push force involved..

Despite these uncertainties, what sprung to mind was a 'jhonny joint' - a ball joint based on a spherical bearing with a hole in the middle, I feel sure you are familiar with them. They are sometimes suggested for use on suspension systems, panhard rods, radius arms, and the like. I expect the 30 deg. deflection you want might dictate the size.

IIRC, to get your 'flat plate' presentation, one plate would have a hole in, to take the stem of the housing containing the ball, while the other plate would have U section welded to it, the arms of the U clamping the ball of the joint.

HTH.

[Bowie69]

Si, have a look a rid eon lawn mower ones, they have something like you describe I believe

Any garden machinery place should be able to get/have them on the shelf, but may need to order the flanges in.

[simonr]

Thanks for the suggestions.

David, A Jonny Joint (or rose joint) is not suitable as it does not transmit the rotation - OK, it does, but only when the joint has reached it's max offset. In this case, it would mean the trailer could rotate side to side 30 deg. I want it's 'lean' to match that of the bike - thus a UJ is ideal.

I'll have a look at Mower parts - that's the right sort of scale of part.

The reason for the size range is just to make it 'look right' and have sufficiently little backlash. I think even a UJ from a socket set would be strong enough, but they have too much slop in them and don't cope well with dust and abrasive environments.

I once had a part which would have been perfect. I think it may have been an Aircraft part. An Aluminium UJ, about 30mm across with a 6 bolt flange on either side about 45mm diameter.

Si

[JeffR]

Could you not use Defender steering column ujs and make flanges to clamp in? That way spares are available from everywhere!

[miketomcat]

So just get a prop uj and install it in a pair of ends off a prop instead of an end and a shaft.

Mike

[Simon Smith]

I can't think of a ride on mower that uses anything like that, and we work on them every day. If they have UJ's they are on splined PTO ends not flanges.

[Bowie69]

Well I've worked on a couple, both Kubota, that had this arrangement for the drive to the hydraulic drive at the back (I think this was what it did, been a while though).

There was the arrangement you mention on the drive to the cutting bed though.

[Simon Smith]

Oh yes, Kubota main propshaft. Havent got a parts drawing here, but beink kubota parts Si would probably need a morgage to pay for them

[muddy]

Tractor PTO shaft ujs and crosses are available in all different sizes some with flange some with 10,20 or 21 splines that are quick release so could double as a hitch? We have charts full of them, vapormatic, kramp and waltershied (sp?) to name a few.

Will.

[secondjeremy]

What about something like a 'Rotoflex' coupling? I know they were used in some 60's - 70's cars but they're also used in industrial machinery - perhaps I've seen small ones?

[simonr]

I had a chat with a place that fixes garden tractors - and he said he knew exactly what I need! He's going to have a look in his shed.

Apparently they are used to couple gearboxes to rotary mower heads on some machines. Thanks for all your help - I knew there would be something out there!

I'll post a piccy when it's all together!

Si

[zim]

Buy a moped

[simonr]

Buy a moped

Don't think that will help! I have an idea which I think could extend the range of electric bikes by up to 25% for the same capacity battery and add a number of other benefits. A moped is not really going to help me find out if it works! Anyway, I have a perfectly good Td5 110!

Si

[Bowie69]

Regenerative braking?

[simonr]

Nope!

Si

[TheRecklessEngineer]

Does it involve crystals infused with mystic energy?

[simonr]

Does it involve crystals infused with mystic energy?

Dilithium?

Si

[landroversforever]

Does it have a small 2-stroke Snake oil engine?

[CwazyWabbit]

Does it have a small 2-stroke Snake oil engine?

A snake oil engine? Awesome! A totally renewable fuel which is in fact in such abundance that we should be paid to burn it

[dirtyninety]

Would a booted CV joint have not worked perfectly, it would allow to the bike and trailer to lean as one, and would allow it to move in the correct planes.

The trailer will have to be fairly heavy to have enough traction to push a 100kg man-bicycle combination!

[ballcock]

Reading your description for it's use the trailer is for propulsion. Would it not try to push the wheel side ways if it can articulate that way? I appreciate the horizontal movement which could be accommodated by just a pin and shackle which would keep the trailer pushing directly through the same axis as the rear wheel. I am no engineer so will accept my thoughts are invalid.

[muddy]

Growing up I had a few different bycycle and trailer combinations that I used to pit lawnmowers in and go mowing lawns, I had trailer onto the seatpost with a uj, clamp onto a rear stay with a spring, and A frame around the spindle like the BOB trailers, the latter was the most stable however I would get the coupling as close to the rear wheel as possible as mine piveted back at the trailer and was a little unstable with a heavy load (120kgs ish) as it multiplied your peddling actions causing a snake effect. However you probably know all this.....

Will.