Compact Bulldog Bone

bulldog bone failure.webp A user has had a "disconcerting moment" with the Bone. The top arm became cross- loaded with the bottom arm impeding the proper upward motion of both arms. Fortunately he was bucked in when this occurred and is OK, and now has a ground level video to demonstrate the problem. If I can figure out how to load it here I will.

Gordon
 
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The Rope Runner has nubs on the main body to keep the lower arms from pivoting at a certain point. Perhaps there's a way to do that with the Bone, or have some type of hump on the lower side of the upper arms so they make contact with the chain link instead of allowing the tips of both upper and lower arms to bypass.

Tyler, I'm not sure that would take a great deal of force. I can imagine If there's enough slop in the unit at its pivot points, the arms could bypass fairly easily, especially on an early prototype version that was made perhaps at lower tolerances than yours. Heavy use could also result in wear at the pivot points to allow a bit of slop.

This is certainly something to be mindful of. I'll take a look at my units to see if they have the same potential issue. I haven't experienced any issues with them. They have been rock solid.

Thanks of posting, Gordon.
 
Please, if you continue with the Bone, put the 3/4" bollard into the outboard end of the top arm with a pin, after the rope is inserted.
 
Gordon, I know you've posted vids before but just to make sure, I think your best bet is to put the vid on YouTube and then link that to here.
 
Aside from just halting proper arm movement, this wouldn't have done anything like cause a sudden drop, would it? I'm trying to imagine the scenario if he wasn't bucked in.

Was it possible to safely switch over to another system?
 
Similar to Oceans comment - putting something on the outside of pair of arms would stop them being able to twist beside the other arms. Would also make the upper arms nicer to grip :)

PS I'll get mine out in a bit to check - but I think there is not play on mine. Yet - perhaps I'm not using it enough.
PPS Thanks for the honest heads up.

EDIT: SO I went out and it can be forced over both ways, but it does take some doing! I will think about putting some tabs on - either epoxied, screwed or possibly ally 'welded', though I'm not sure sure what heating up ally would do to its strength. Countersunk screws through the inside of the arms would not hinder the rope mounting path.

EDIT: I reread Oceans comment - and his humps idea is different and probably simpler from a manufacturing POV so I've corrected my first sentence.
 
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Well I'm sure you're disappointed Gordon but at least it was caught safely and we all know you'll find a fix.

I'm supposed to have another one in the mail and I'm sure others too. Are those on hold? Or should they just be used with the additional bollard?

Good luck and let me know if I can help in any way.
 
For All users, if you elect to continue with the bone, please insert the 3/4" bollard in the top arm outboard hole with a locking bolt after the rope is installed on the Bone.
In the meanwhile I will work on a solution. Dave and Reed have both suggested making the end of the top arm fatter on the outside edges and I will be pursuing that possibility today.

As for those that have not been mailed out, I am asking that each make a decision as to whether they want me to cancel their order, or put their order on hold while I work on a solution.
 
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15532705597_8d8683dece_z.jpg

A couple of threaded domes the same width as the arms would make a good retrofit.
Two pairs for top and bottom for the paranoid.
 
IMG_1002.webp Thanks to all for your suggestions and encouragement, it means a great deal to me. the handles shown are the 1/2" x 3/4" bollards that I have on hand. I think I will end up with 1/4"x 3/4" on each side instead, which should be sufficient.
 
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Sure you already know this Gordon but I just tested mine with bollard removed on Vortex and it runs perfectly.

Good news on the modification. Does it seem to resolve the issue?

Great idea Paul!
 
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So looking at the pics more I think I understand better what's happening.

Is the cross loaded lower arm able to bypass the upper arm instead of butting into it, causing the device to get stuck in the release position? If so, that means the intention of the new modification is to prevent bypass?

Sorry to bug you with questions but just trying to understand the failure and the fix. Thanks so much.
 
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