Dual Cam Setup

JBarca wrote:
The set screw drug the frame and headed towards the "bottom" of the frame. In order for the dig marks to go that direction the DC arm had to be lifted "up". Agree Yes/no?

I originally wrote that the chain was pulling up.... but went back and changed it.

When the WD bar is under tension, it's trying to pull the chain down. If the WD bar was centered exactly under the chain, there would be no twisting action. Since the WD bar is to the inside, there's a down force somewhere on the cam and the chain is resisting that force on the end of the cam. I think this creates a twisting action. This is why a small movement can be observed when the bars are snapped up (or when the tongue is let down - I'm not sure when it showed up).

JBarca wrote:

Now the frame crush at the DC frame plate. This pic aligns with the set screw rotation. The DC arm had to rotate "up" in order to crush the frame in. Both the set screw and the frame inward crush support an upward force doing this damage.

Yes, counterclockwise when facing the trailer from the coupler.

JBarca wrote:

If we determined the snap up area failed from the chain force pulling "down" on the snap up, and the DC area pulling "up" on the cam arm, then the 2 areas of failure happened at different times and from different force directions. Agree yes/no?

I was all ready to disagree, but I see your point. So I went back and changed my story some - to discuss this twisting action with the bar pulling down in one spot on the cam and the chain out at the end.

What if the spring bar is loading the cam at the inside keeper flange, basically as far away from the chain as possible. Also assume that since it's all new and not worn in, that the bar is only contacting the cam on a small portion of the bar - at that flange. I'm stacking the deck here to see if my idea is even remotely possible. So, the bar is pressing down on one side of the cam, and the chain is resisting that force on the opposite side of the cam. This would produce a twisting force, but I don't know how much.

I don't have the bar here, or else I would get a photo to see where it's starting to wear....

JBarca wrote:

This is why I think there are 2 separate events that caused the failures. The force directions to cause the failures are in opposite directions.

I'm trying to picture the load changing direction on the chain at the cam mount. Can it? In order for there to be any damaging forces at all there needs to be tension on the chain. Won't this tension always be from the same source - spring bars trying to pull down and chain/snap-up resisting?

JBarca wrote:

Keeping an open mind to this, after all this review is there anything else on that very short trip you made that sticks out to cause forces in the directions we are talking about? A hard bump from a pot hole etc?

I can think of two compound angle turns

One was a left out (and then back in later) the driveway.

The other was a compound angle right turn, leaving my neighborhood out onto the main street. I'm pretty sure we've done that turn a few times as well. It's not a hard angle, but the trailer is higher. If I had to pick a turn/event candidate that would be it.

When coming back we did not do the reverse (left turn) into that compound angle turn.