Stridergdm wrote:Not really. A jigger really tends to refer to a 4:1 (or 5:1 depending on orientation) haul system comprised of two double pulleys (you can do it with 4 separate pulleys but you lose efficiency as the pulleys are on an angle) that can be used to haul or lower.
A 4:1 or 5:1 would seem to be a pretty easy extension from a 3:1, and I'd say that a mechanical advantage system is still the same system even if all that advantage is eaten up by friction, it's still the same beast whether you construct it with carabiners, maillons, or pulleys. Perhaps teaching MA pulling systems and then the jigger and RLRH as specific applications of these???
This way perhaps keeping the two separate?
Stridergdm wrote:The amount of friction (which is a design feature) of the RLRH precludes its use as a haul system.
It's still the same basic structure though, and yes I recognised the friction as a design feature and the thing that probably lets the hitch survive the shock loads it's been tested with. People with nothing else still use carabiners to construct pulley systems though, Petzl's documentation for the Tibloc shows these as well as heaps of other materials.
Stridergdm wrote:Nice smiley!
Stridergdm wrote:For example, given the subject at hand, if someone used a jigger in the place of a RLRH for a belay line and the belay line is shockloaded and a pulley in the jigger fails, the first question a lawyer is going to ask is, "What evidence did you have that a jigger would work in that situation?"
Ron and NZcaver were suggesting connecting the haul directly to the anchor and doing away with the RLRH right? not as above where the RLRH is replaced by a jigger. (perhaps we are getting to a important reason to keep them separate which I suspect is what Stridergdm's example was subtly trying to show me.
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Which leads me to thinking if your haul team are inattentive or the message to them is late and they get the load stuck under a balcony or similar with the haul line pulled tight a jigger depends on being able to raise the load even slightly in order to let it back down right? (to release a PCD or put in a descender?) in this case that might not be possible, a RLRH would not be similarly constrained. Or am I wrong here?
Funnily enough the ukcaving board was dealing with a similar topic (but smaller scale) when talking about belaying etc with mini-traxions and the same problem came up there.