Hitch Climber Pulley on Bridge - WARNING

[bonner1040]

http://www.sherrilltree.com/About-U...se-of-Hitch-Climber-Pulley-on-Harness-Bridges

We received a warning at work about this and then I saw it on facebook... Thought I would share.

Stephen, let me know you saw this buddy.

 

[CurSedVoyce]

Saw it.. Concerned me some. Been keeping an eye on the set up. Not really seeing the torsion on the plates they describe, with they way I have it set up.
I am going to retire it soon though and switch to a pinto. When I do, I will send the pulley to WeSSpur for testing.
I can see the weak link would be weakinging the plates and the shaft of the sheeve with excessive torsion.
Amazing the concern also o as high as the pulley is rated as well.

 

[rangerdanger]

So the concern is the pulley side plates seeing forces and becoming separated right? Because I have one hitch climber and have seen it at other comps, where the plates separate for some reason. I retired mine, but myself and others have found it odd and disturbing. And I never used mine for anything but tending my hitch.

 

[CurSedVoyce]

The larger line they list (14mm) would be a huge consideration.. The high mod bridges would also be.
Keeping the pulley captive with a screw link and clipping into the link instead of the pulley seems to help IMO and is how I set mine up. My bridge is PI which is 11.7 mm. And also aliminates the high mod rope bridge issues. A tad longer than what came with the saddle as well, better bend radius.
I am noticing wear. All gear wears. Daily inspection and replace when necessary go a long way in minimizing risk. She is about to be retired. Gave me good serivce or better than 3 years as a hitch tender and then bridge pully. I can not complain.

 

[canadiantreeman]

I like it for a bridge pulley and would have the same concern if I loaded the thing like an idiot. But, I don't.

 

[bonner1040]

Just a heads up!

I knew CursedVoice used it as a bridge pulley...

 

[canadiantreeman]

Haha, thanks. I definitely puts it in perspective. Too bad, I might have to get me a couple rings instead.

 

[bonner1040]

I tried using a swivel for DRt and it didnt work out, went back to rings, but then since I started climbing SRT a swivel works great.

 

[pigwot]

Heh, just dug out a swivel this morning... CMI Axis rated at 9000 lbs MBS

 

[NickfromWI]

How would apple extreme torsional loading in this application? I'm confused.


love
nick

 

[bonner1040]

I think they are saying that the angles the rope exits, on a rope bridge while the user is twisting or falling, can bend the sideplates off the bearing.

 

[Adam_P]

Thanks for posting this. I'd be curious to see a pic of one of the HCPs that's worked apart.

A pinto on a bridge would be bomb proof for sure, but I bet the 3 holes in the HCP would be missed.

I have a dmm swivel on my bridge and you an run it with the swivel (bridge in one eye, biner in the other) or bridge and biner in the same hole and swivel as a third attachment point. I believe it's rated in all directions and runs nice and smooth on my bridge.

 

[woodworkingboy]

I figure that if you are confused by how the application can lead to trouble, you have nothing to worry about.

 

[CurSedVoyce]

Thanks for posting this. I'd be curious to see a pic of one of the HCPs that's worked apart.

A pinto on a bridge would be bomb proof for sure, but I bet the 3 holes in the HCP would be missed.

Yes it would, HC keeps it real tidy.

 

[DMc]

I figure that if you are confused by how the application can lead to trouble, you have nothing to worry about.

Yes, ignorance works so well at keeping you safe. How often do those of you that use the HC on your bridge use the two outside holes and for what?

Dave

 

[bonner1040]

When I was using mine on a bridge I connected the HH to hole 1 and the standing line to hole 3 in DRT mode.

When climbing DRT or even SRT I have tied a closed system into the other hole for double crotching.

It wasnt that often.

 

[CurSedVoyce]

SRT, tether to hand ascender hole 3, main link to prussik center hole. Wraptor tether hole 3. Double crotch a lot, holes 1 and 3. Climb systems stays on 1 SRT and Ddrt.

 

[DMc]

...I can see the weak link would be weakinging the plates and the shaft of the sheeve with excessive torsion...

Yes, if you look at the size of the sheave pin, you can see it is smaller than most of the micro pulleys that have floating side plates. It is more than adequate for straight shear loading and the design's intended use and less adequate for resisting torsional side plate loads.
When used on a bridge and the two outside holes are used for support from different points, as is common with double-crotching, any twisting that the climber does while suspended can potentially create a torsional load. The reason for double crotching is to gain more stability or safety in awkward situations. This means that there is a good chance you will have your full weight on the bridge when you need to reach out and twist to cut that limb on the other side. Side loading the HC from the bridge will not show the wear marks on the side plates that you can see from a running line because it moves/travels such a small amount, comparatively.

Dave

 

[CurSedVoyce]

I'm gonna die ......
























Agreed about the pin... The way I have mine set up, not so worried about the torsion from multi connection, yet I agree with the hypothosis.

 

[stig]

Eventually, yes!

 

[CurSedVoyce]

So who wants to do the break test with out me attached??? Dave?

 

[wiley_p]

So who wants to do the break test with out me attached??? Dave?

I'm trying to think how to rig it to mirror the "problem"

 

[CurSedVoyce]

I am more interested in the supposed torque wearing it gradually like cycles to failure. Curious to see how much my system supposedly compromised the strength.

 

[Evan Sussman]

Aw, so sad. I think I'd miss my three holes to tie into. I frequently use extra holes for clipping my lanyard srt to, when chokeing on a limb, if lanyard drt if it doesn't have to be quite as far away. I've definitely seen the torsional loading that this is talking about. I guess it's time to take a close look. It would be nice if DMM or someone made one extra beefy for this. or better yet, combined a swivel with three holes!

 

[CurSedVoyce]

Still have to order that Pinto. I find it VERY hard to take that HC pully off my rope bridge. But it is time to change out the bridge again.. SO next WesSpur order next week with the cabling order I have to put in. Then I really think I'll have Dave test it at WesSpur to see if my system weekend it at all. The weak link should be the pully shaft by my inspection. We shall see. My theory is, since I incorporated the quick link between the HC on the bridge and the biner on the HC tending system, I incorporated more swivel ability into the system. This should have alleviated some of the torsion wear, from twisting in the system, the caution speaks of.