Shaft Length - Cardanic Design and Radial Displacement

It is just a bit difficult to advise base on so sketchy information a bit of a sketch could have been use ful.

As I understand that you have a telescopic shaft between the engine and the gear box. With copupling on both sides.

If this is the case, then the length if the intermediate shaft can be adjusted. Consult the coupling manufacturer, give him the end dimensions and ask him to design for you. However there is a minimum limit for this shaft length. If it falls below this limit, it may be better to go for a single copuling instead of two, with may be extended hubs.

Again the coupling manufacturere may be able to guide you about the best coupling configuration based on the distance, load and type of load.

And OEM means the Cplg manufacturer ? then he is correct, The total design of the coupling is based on the load, angular misalignment. As the shaft length is reduced, the angle increases and hence the coupling requires re-design.

Hi sb,

OP calls it a cardanic design which I would take to mean Cardon shaft which means universal drive, ie two universal joints and an intermediate shaft, the length of which could be quite important with regard to the distance between the equipment and the allowable tolerances for angular misalignment and parallelism. As you say not really enough information to form an opinion.

Apologies sb - you are quite right. I just assumed that he could not spell. This is what he means I guess. Horrible things.

Still asking for trouble by shortening the spacer piece unless he knows exactly what he is doing. Listening to the OEM is always a good start.

Unfortunately it looks he does not and he is at the best going to blow up the coupling.

And I have seen the drive/ gear box DE bearings as well as the shafts going to heaven hell due to these minor modifications (at least the user thought so).

Once at our works- of course it was a very highspeed gear box, the shaft broke off during shop testing, broke the guard and flew off about 30-40m - very fortunately nobody was hurt. And that was this coupling modified by our testing deptt.

"Currently I have a problem to modified the shaft between gearbox and engine which is we need to shorten the length due to some problems occured"

Could you quantify "Shorten" please.

Any of these couplings look similar to yours?

http://www.ktr.com/kup71_web/kup71_web01.asp?LA=en

If not a pic or link to your particular type of Cardan coupling would be helpful.

It seems you are just going to be storing up a quality problem for the future...

Its quite critical since the OEM doesn't recommend that, but just buying another one.

Why don't you take this advice, or do you have a wharehouse full of the wrong part?
Is this a one off or a production part...?
If it's for a production run, I'd be seriously worried as it could all come back to bite you on the ar$e, and end up costing more that getting the right part in.
Del