Fatigue properties of welded steering shafts

[gearman1234]

WE have one appliocation for steering shaft for material handling equipment. Due to difficulties observed in shaping blind splines in 4140 shaft ( H/T to 28/32 HRC) we are changing it to broaching one end ( 3 inch long) and welding it to the other long end ( about 13 inches long).

My main concern is the fatigue properties of this welded joint. I do not have any information about the torque and no of life cycles.

Does any body has any information about the fatigue properties of such an application when a welded joint is used?

 

[GregLocock]

Can you manage a shaft and socket set up, with a couple of inches of engagement? if so then I think you can be very confident of the result. As a safety feature you could stick a nut and bolt through it fr the prototype, until you realise it is strong enough without.

Cheers

Greg Locock

 

[gearman1234]

Yes. That is how we are making the joint. But the allowable engagement will be 0.5 inch max. I will check if more engagement is possible.

But the suggestion to put a bolt thru will definitely help in strengthening the joint.

Greg Thanks for the help.

 

[GregLocock]

As with any zero redundancy weld in the steering gear it is industry practice to proof test every part, I'd suggest to 10 or 20 times the maximum expected load.

Your shaft in socket engagement is a bit short, I'd really try and get enough length in there so the joint is operating in torsion, not combined torsion and bending

Cheers

Greg Locock

 

[gearman1234]

Thanks for the info. I understand what you mean.
Is there any website or technical reference book where I could find more information about steering gears design, manufacturing and problems etc. ?

I would try to see if we can provide more length by changing the design.