What is the weak link in a cam?

I've spent the morning marking my gear, and took the opportunity to give it all a thorough going-over.

In reviewing the load ratings on my cams I noted that the C4 #6 through #.75 are rated to 14kn, and I grew curious as to the weakest link in a cam, given that it's obviously not the lobes. (For the record, I don't have a 5 or 6, just looked those two up online.)

My guess is that it's the wire, but I'm sure that someone here can enlighten me.

Going to guess here and say it's the cable swag. That or the webbing. Geir, where are you??

it totally depends on how you load it. in 'theory' you should load it axially along the cable, but in 'practice' sometimes that isn't purely the case. most (non-alien) structural failures that i have heard/read about involved buckling of the cam lobes, most likely due to off-axis loading that resulted in bending of the lobes.

C4's pulled to failure will generally snap at the wire thumb loop. The wire fails, not the webbing. I think lobe buckling is more common on the larger sizes if I remember correctly. Of course this is all past the 14 kN rating.

My $$ is on the QC (or lack thereof) process.

Many years ago I watched at the BD facility in SLC as they pulled a #3 camelot to failure, the sling broke at something like 4500 lbs

I would say for the most accurate answer contacting BD would most likely be your best bet. I have contacted them previously with a similar question and recieved a response pretty quickly.
BD customer Service emails

tradryan wrote:C4's pulled to failure will generally snap at the wire thumb loop. The wire fails, not the webbing. I think lobe buckling is more common on the larger sizes if I remember correctly. Of course this is all past the 14 kN rating.

I seem to remember smaller cams that were pulled to failure having the axle bend enough so that the lobes torqued and no long pushed perpendicular to the walls, causing it to fail.

Those were pull-tested to failure though.

That's all fascinating info. Does anyone know of published pull-test results on trad gear?

What is the weak link in a cam?

The sketchball placing it.

Stich wrote:What is the weak link in a cam? The sketchball placing it.

Stich wrote:What is the weak link in a cam? The sketchball placing it.

Answer: the link cam

David Appelhans wrote:Answer: the link cam

Link Cams' weakest link is that thin metal between the links as you can plainly see. It tends to fracture when the cam is loaded at an angle, which is how it is usually loaded of course since it's the real world.

tradryan wrote:C4's pulled to failure will generally snap at the wire thumb loop. The wire fails, not the webbing. I think lobe buckling is more common on the larger sizes if I remember correctly. Of course this is all past the 14 kN rating.

Stich wrote:Link Cams' weakest link is that thin metal between the links as you can plainly see. It tends to fracture when the cam is loaded at an angle, which is how it is usually loaded of course since it's the real world.