Dismantling a Universal Joint

Hi,

I have purchased a metric UJ from RS Components and need to undertake some machining to make the bore and OD suitable for my requirement. The slightly protruding trunnions have made me give up trying to hold the UJ in either 3 or 4 jaw chucks). To that end I'm seeking advice on how to dismantle the UJ please. The centre block has a line etched across one face and I'm thinking that would be the continuous trunnion and I'm planning to drift it out. However the opposite housing piece has a letter "c" engraved on it which could also mean continuous. I've got a couple of snaps. Any advice most gratefully received! Cheers, Vernon

Vernon,

I may be wrong, but: I think you would regret dismantling it ... it will never be the same again.

I would turn a split collar to increase the effective OD; modify the bores, and then re-mount on a mandrel to modify the OD.

... I'm sure you will get a variety of alternative suggestions

MichaelG.

I agree with Michael that is not a good idea to try to dismantle the UJ. I would have thought it was possible to grip them in a 4 jaw chuck with the jaws at 45 degrees to the trunnions.

Les.

I had a similar problem a few years back in modifying some 1/2" universal socket drives for the radio telescope I was building. The metal is bloody hard and I eventually ended up drilling the thing with a tungsten carbide drill and fabricating adapters from mild steel with roll pins to hold the bits together.

Always do the simple thing, as Michael G , split collar round the plain ends. Job done !

Thank you all for your advice. The clear message is don't dismantle the UJ so I'll take that on board.

The reason I've had problems mounting one end on a 3 or 4 jaw chuck is that the trunnion ends are slightly proud of OD of the main body and at least one always interfere with at least one of the jaws. I had thought of grinding the trunnion ends down below the OD and then trying to mount it in a chuck and I guess I'd have to go that way if I sought to use a split collar.

Bit more thinking about then I'll give it a go.

Thanks again.

Vernon

Perhaps modify the equipment and not the UJ ??

Not possible to fix in 4 jaw with trunnion ends in gaps between jaws? Even with packing?

Regards Ian.

Make a collet to suit the o/d, then counterbore aprox. in the middle to clear the pin ends. The slit in the collet should allow enough clearance to pass the pin ends ?

Thanks for the recent replies.

Speedy, it's to reinstate the table drive on my Tom Senior mill. I'd have to take the knee off and machine the PB housing to change that end. and I don't fancy that.

Circlip - I've tried at length but can't avoid all the trunnions.

Gordon - I think you've put me on the right path. I can see how that would work. Thanks

Regards,

Vernon

I had to machine 8 UJ's for my moulding machine in my workshop. They each took drives from 3 HP electric motors so were larger than yours I expect. they came with 10mm holes & had to be increased to 15mm with a woodruf key slot

I had nothing to do the key slot so tried a bodge which may be of use to you if you have to put in a key slot.

I worked out where the circumfrence of the hole came & on the circle I centred a 10mm drill & bored a hole.

When I drilled out the 15mm hole ( may have been 18mm memory a bit slow these days) I was left with a semi- circular slot/groove . The woodruff key in the motors stood up about 5 mm so by grinding a round on that half of the key I was able to assemble it. The machine worked daily for the next couple of years machining 1000's metres of timber.

For the model engineer it must be easier to broach the slot if partially cut out. One would only be taking the corners out of the groove. I mention this because I have never seen it written before & expect that it could be adapted on UJ's with the full hole already cut by sticking a sacrificial plug in the hole & drilling down the join to get the same effect.

I expect that the purist will sigh, but it saved me blowing £ 30K for a new moulder for 2 years !!!!

Thanks for the tip Sam.

The original installation had the shaft pinned to the lower UJ and was a sliding fit with the upper drive shaft which featured a keyway. I'll use a slot drill to cut the keyway because it's straight into the shaft.

Plan now is to turn the end of a 1/2" shaft to force fit into the UJ. Drill and taper pin. Place shaft in chuck and turn OD of one end of UJ body to 15/16". Fit and pin shaft with keyway to other end of UJ. Cut first shaft to length to suit knee housing gearbox. Apply new gaskets. Fill gearboxes with oil. Stand back and admire my work.

Vernon