double cardan joints

[Oakley45]

I wonder if someone can help me, I am creating a vehicle that will tilt into corners, I decided to use a centrally mounted differental and drive shafts out to the rear axles, the problem I am encountering is getting the power through the large angles required, up to a max of 47 degrees each end, the vehicle only tilts 30 degrees but due to the location of the axle end and the differential shafts the larger angles are required.

I am wondering if it is possible to use double cardan joints, a pair of them one either end of the drive shaft, although I feel that the shaft would need to be supported though as no support if offered by the joints to the shaft.

Many outer cv joints available on cars are capable of the large angles i require but then I will have to attach a flange to them so that can be attached to the rest of the axles. The CV joints are hardened so if I was to weld them that would not be very strong and I may have to get them rehardened.

Anonther problem I have encoutered is the pluge required, which is approximatly 45mm

does anyone have any suggestions? sure there are people on here with more knowledge and experience than me. apologies for my ramblings

 

[MikeHalloran]

Forty years ago, when I worked in Ford's driveshaft factory, some of the high end car lines used double cardan joints at both ends of the shaft. The shaft was not free to flop around and did not require other support. There was some kind of link between the extreme yokes; I think it was a ball and socket on central stalks that extended through the crosses... or something else; it's been a while.

I.e., in at least that case, a double cardan joint was not just a couple of regular u-joints mounted back to back.

I'm not clear on why you require flanges. Many cars today use unitized wheel bearings with an internal spline; the outer yoke spline just slips in.

As for plunge, I guess you'll need a ball spline. I think 'tripod' joints can take some plunge, but I wouldn't bet they could accept as much as you seem to need.



Mike Halloran
Pembroke Pines, FL, USA

 

[GregLocock]

45mm of plung and 47 degrees of articulation is way outside of any tripod jint I've seen. A couple of minutes sketching would indicate the likely size of such a monster.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[MikeHalloran]

Even if you (somehow) used the tripod just for plunge, it would still be an unusual tripod.

But wait; if the vehicle leans into corners, and the wheels similarly lean into corners, and the power level affords it, chain or belt final drive on trailing arms starts to make sense.



Mike Halloran
Pembroke Pines, FL, USA

 

[DanEE]

No idea how many vehicles in production today use double cardan joints, but if you are looking for possible sources Toyota has used them for years on their 4x4 vehicles and still uses them on current production 4x4 vehicle driveshafts.

No idea what the max angle would be.. they use a ball joint between the 2 U-joints, and are massive as mentioned above.

link to pictorial of the rear drive cardan shaft on my 2000 4Runner..

http://personalpages.bellsouth.net/d/a/dandeman/photos/reardriveshaft.jpg

http://personalpages.bellsouth.net/d/a/dandeman/photos/driveshaft.jpg