cv joints for steering

[san]

hi guys,

i've seen few pictures in which cv joints are installed for steering. i know that cv joints give constant velocity output. then why do we've to use 2 cv joints on the steering assembly?? does it help??
i read that two hooke's joints are a must to get constant velocity output. does this apply to cv joints as well??

kindly provide me the specifications of the cv joints that u've used on your cars'.


san

[san]

hi guys,

i've seen few pictures in which cv joints are installed for steering. i know that cv joints give constant velocity output. then why do we've to use 2 cv joints on the steering assembly?? does it help??
i read that two hooke's joints are a must to get constant velocity output. does this apply to cv joints as well??

kindly provide me the specifications of the cv joints that u've used on your cars'.


san

[Jersey Tom]

I think universal joints are pretty common.. use as few as possible. 2 does not help. It is just a packaging requirement sometimes.

[Marshall Grice]

I think it's worth noting that I've never seen a CV joint used in an FSAE steering linkage. They're all U joints of some sort. As Tom said, only use 2 if 1 won't work(angularity wise).

[kwancho]

I was under the impression that a single U-joint at an angle has a sinusoidal output for a constant input, and that a second one at the opposite angle would bring it back to constant. Is that not true?

[Kerry]

I believe you are right, Alex. If you don't have the same angle at both ends of the shaft you can phase the joints accordingly to produce a constant velocity.

San, I would say one CV joint would probably do the trick. I remember reading another post on this topic and popular opinion seemed to be that you can get away with just one U-joint in an FSAE car for reasons that I cannot recall, but I would be wary of this. We've never needed to run U-joints on our steering column (top mounted rack with a straight column) so I can't reccommend a place to look for smaller CVs.

[san]

hi kerry
thanks for your help
we have decided to use a single joint universal joint which has a specification of ::
internal diameter- 16mm
outside diameter-- 32mm
length-- 95 mm
this is a key type universal joint

wat say about this??

[Brian Evans]

Why not run an Apex joint, same as everybody else? Very small and light.

Brian