Micro Hauler from fresco

PUClimber

PUClimber

Location
Indiana
Hey guys,
I just went to the guys link on the helmet on sale and saw a micro hauler and was wondering if anyone could shed some light on this little gadget for me. It looks interesting enough but just looking at it I can't figure out how exactly it would work unless it is supposed to work like a hexaratchet pull sent to the top of a tree single line then climb drt off of it.
Here is the link

Fresco Micro hauler
 
Generally such a jig is used for 3:1 Z-Rig pull with a hold by cam. When on hold though, it is only a 2:1(unless cam is on anchor and not load end, then 1:1); 2 legs of support/pull on Load ; ending at cam. When you go to pull it; you make the 3rd leg of pull for 3:1 ending at your hand; or in other words another leg of pull past cam. As any Zrig/3:1 can be 2 handed for 4xpull of 1 hand. Piggy backing systems with 1 hand pull for 9x; 2handing into that 12x; best at 2 handing a Z inset inside the other for 16x pull of 1 hand. Usually for such a purchase; you'd need more sheave(s); giving more friction to reduce force you are trying to multiply. A Z-rig made in just rope on ring and butterfly giving only 1.65x effort pull on Load or so from the 3x potential of the path of forces; due to friction losses/ inefficiencies. A downside to 2Handing and insetting is that usually less tension is on anchor than load; but these strategies place matching tension on anchor as load.

i'd imagine that would be a bushing pulley (more friction than bearing) and the small sheave diameter/ratio not give much leverage over that. Both factors combining for a less efficient pulley; and the small sheave making larger leveraged bend in line.

But, it sure is nice to pull and have the hold of the tension available. Also can get more power on it then; as you are then freed to impact into the system, and have it hold the tension.

Alternatively you can choose to get a larger, bearing (both factors combing for more pulley efficiency; and less leveraging against line tensile) prussik minding pulley. Tradeoff is needing prussik, and some 'play' in the system/ hold function not as instantaneous as cam; but then doesn't just pinch/ tear at line like cam.

All depends on your needs, lines, style of attack etc.
 
I think what spidy is saying is that its a 3 to 1 set up that has a cam that will maintain a 2 to 1 ratio when you are not pulling. Hes also saying you can use a prussik to do the same thing theres just more play.

From the looks of the device they use a small pulley, which reduces, in my opinion the advantage of the system, larger pulley more effective use of your pull. The systems in my opinion are rather easy to set up with day to day to tools we use in our industry all ready
 
You would need to get a double sheave pulley to complete the rig.

Brion Toss calls these block and tackle arrangements jiggers or Handy Billys...I like that name :)

If half inch rope is used to rig one of these HBs you will loose effeciency when the large rope goes over the small sheave. A better design would use a smaller diameter rope.

In BT's book he describes how to rig an HB. Start out by calculating the maximum load you will apply to the input rope leg. In tests, on level ground and good footing it's calculated that a person can generate about 80% of their body weight in a pull. A 200# body will generate 160#. Run that through a 4:1 and you only can move about 640#. Add in a safety factor that fits the exposure, 10:1 isn't a bad comfort buffer.

Considering this there is no reason to rig up an HB with climbing rope. Use some good low stretch accessory cord that the cams will still bight onto.
 
Ummmm i think that rig would work as a 4:1 compression jig; not the more common 5:1 that would take another double sheave on anchor. Also, the prussik to piggy back on another rig or host line would go on the 4x pull end; with cam i'd think. When hand releases pull tail/ Bitters then, same pressure can be held on load; but cam etc. is holding a 3:1(not 4:1)and opposite pulley/end now has more force on it even though (whole)cam end stays the same tension output. This must be taken into consideration when nearing cam limits etc.; measurement on hand hold posititon not same as cam position.

Pulley friction will be friction of sheave over axle; but then sheave also takes leverage over the axle to fight that friction. These 2 factors give efficiency/friction loss of pulley. We only fight friction at compressing/ drawing rig together. At hold or extending rig/ lowering; friction helps; does not fight us.

This drawing is large 280k; it shows a prussik instead of cam to hold line for you; it is different use than prussik used here in Kevin's device(i just figured prussik was easier to draw!). Cam or prussik go in same position; pulling out of (to hold load for you), not into the pulley they are mounted on. Drawing example could have another prussik to use to make system grab load line or another rig.

Insetting would be to take a 2nd 3/1 and make it pull on the 2handing pull points shown in drawing. 2handing raises anchor pull forces to match load pull forces like a cam hold does.

edit: if anchor takes more tension than load (like a Zrig lifting with 2x end); prussik/cam hold lowers anchor pull tension; to equal the load's end pull/ tension

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