Cornay Joints

Anyone ever tried the cornay joints?
They have some interresting video's here : http://www.drivetechnologies.com

But they don't seem to be replying to emails. What do you guys think about it?

Hard to tell what to make of the Cornay joint;  the website gives no details of how it works.

I'd wait this one out.

On this link http://www.drivetechnologies.com/page6.html they have some video's which explain exactly how it works.

This place : http://www.bigelowgroup.com is a licensed manufacturer, With a video here: http://www.bigelowgroup.com/40_bigelow_cornay.cfm and http://www.bigelowgroup.com/technology.cfm

The Cornay appears to be a viariant of a cardan joint. Cardan joints only become CV joints if you pair them.No clue as to their claims for up to 45 degree angularity.A ball type CV joint is good for about 50 degrees.

Im more interrested in the claims of zero vibration. They also claim high torque figures, over 2000ft/lbs, which seems a bit much for a system being driven by such a "thin" ring... I don't know, they don't seem to answer my questions via email, ill see about giving them a call.

A cardan join still ataches with a center piece where the cornay joints atach with the ring on the outside.

Dynamically it just looks like a double cardan joint to me, based on the second video. It looks a bit less agricultural (they are used on the PTO shafts of balers and so on) than adouble cardan, but I think it'll be the same.

At least one driveline supplier is pushing double cardans as a substitute for conventional CVs in some applications - they are probably more efficient than the six balls in groove type, but no better than a tripod. On the other hand they have higher articulation angles and less backlash than a tripod.

Cheers

Greg Locock

Thanks Greg.

What kind of vibration does a tripod have according to the cornay demonstration video's there seems to be almost zero vibration, I was wondering to what extent, if any this can improve traction if vibration is completely eliminated.

Here is also another alternative, mostly for strength, but any opinions on these:
http://www.turbomagazine.com/tech/0205tur_unbreak/

One of the neatest designs I have seen is the Thompson Coupling. It is more complex than the elastomeric bush coupling, but offers high potential:

http://www.cvcoupling.com/thompson_coupling/index_coupling.html

So far it seems to be just an idea waiting to happen...

mart

GraviMan that is very impressive.

I haven't seen any practical issues with vibration from tripods or ball in groove joints, so long as they are within their articulation limits.

Theoretically you'll see a bit of third or sixth order, but it is not much.



 

Cheers

Greg Locock

Thanks Greg.

A double cardan should have low torsional pulses/vibration, but wouldn't it tweak the input/output supports with the secondary couple just the same? I believe the secondary couple is what drives my poor old Volvo's diff and center-support nuts.

Yes, with a double cardan you still have to accelerate the innards of the joint, so you still see some nastiness at second order.

I've never used one in a high speed/refined application, so have no idea of their relative merits in practice.

Cheers

Greg Locock

Secondary couple is term used in SAE Driveshaft manual.  I think I recall It is not a torsional thing, but a transmitted torque related couple acting in the plane of the diveshafts.  I also think I recall it is trying to straighten out the angle between the shafts.  If the drive shaft meets the diff at an angle, the axle supports must restrain the diff nose from  bobbing up and down at 2X. The reaction is trying to Tweak the driveshaft in a U at 2X.