Mechanical Advantage Kits- the Tom Hoffman U- Rig Kit, or something else?

H

hseII

Participating member
Location
United States
What MAs are Y'all Using?

What do you like about your MA setup?

What would you change/ adjust/make better?

Is anyone using the TH U-Rig?

What is the reasoning behind the Tom Hoffman U-Rig Kit not using 2- Swivel double pulleys?

Does this route make the kit more useable in other methods?

Thank You.
 
I am not going to weigh into this, as an expert.
I am NOT a mechanical engineer.
Nor have I studied friction factors, bearings, MA setups, etc.

I did however, relatively recently, attend a presentation by Taylor Hamel (DMM rep / consultant) on this subject.

He did demo's with a load cell, setting up MA systems with ropes thru:
1. just carabineers,
2. "standard" pulleys, and
3. high efficiency pulleys with roller bearings, etc.
It was the best tree related presentation that I have ever seen !

The differences to lift, and to lower, were astounding !
I was slack-jawed dumb-founded !

Just because you set up a 6:1, does mean it is anywhere close to 6:1 easier ! ! !
You need REALLY good low friction bearings !

I don't know if Taylor has this type of info on line, but it would be outstanding !

(Thank you TreeStuff Crash Course)
 
Last edited:
GregManning said:
I am not going to weigh into this, as an expert.
I am NOT a mechanical engineer.
Nor have I studied friction factors, bearings, MA setups, etc.

I did however, relatively recently, attend a presentation by Taylor Hamel (DMM rep / consultant) on this subject.

He did demo's with a load cell, setting up MA systems with ropes thru:
1. just carabineers,
2. "standard" pulleys, and
3. high efficiency pulleys with roller bearings, etc.
It was the best tree related presentation that I have ever seen !

The differences to lift, and to lower, were astounding !
I was slack-jawed dumb-founded !

Just because you set up a 6:1, does mean it is anywhere close to 6:1 easier ! ! !
You need REALLY good low friction bearings !

I don't know if Taylor has this type of info on line, but it would be outstanding !

(Thank you TreeStuff Crash Course)
Click to expand...

Tree Stuff is out of the "Rescue" Pulleys, and I'm looking at the 1.5 & 2.0 Omnis, and trying to not justify the extra 2kN.

I was thinking of using it mainly as tensioning for speed lining, especially when using 2 base anchors.
 
Last edited:
The 2.0 double is a hefty pulley. I have been looking into this as well. I traded a few emails to TS this past week about stocking the P21/22 singles and doubles.

The Omni 1.5 double is not prussik minding so my guess is that's why he doesn't used one on each end. Don't see any reason why a system with Omni 2.0 doubles on each end would not work if you want a hefty/expensive system.
 
Ragnar said:
The 2.0 double is a hefty pulley. I have been looking into this as well. I traded a few emails to TS this past week about stocking the P21/22 singles and doubles.

The Omni 1.5 double is not prussik minding so my guess is that's why he doesn't used one on each end. Don't see any reason why a system with Omni 2.0 doubles on each end would not work if you want a hefty/expensive system.
Click to expand...

The 2.0 are $41/per more than the 1.5.

I don't really think the 2.0 is worth the extra $80 over the 1.5 for me, but again, it's only $82.


Yes, Prusik Minding.
 
knudeNoggin's standard quote on an all rope trucker's hitch 3/1 setup
>>is getting only 1.5x after frictions.
(i think knudeNoggin is about smartest knot guy ever came thru here,
also IGKT, and most quoted in online and hardcopy texts i've seen in recent years)
.
Going over about 88% pulley efficiency starts co$ting much more;
squeezing the last few drops of efficiency out.
Just as pulley powers add/multiply up quickly, so as do the inefficiencies of their frictions!!!
.
As any tools, there can also be art, beyond the mechanics.
2handing(4th and 7th rig in pic below) a 5x1 can give 8x1 of effort + 5xBodyWeight, with less friction than 8x1 rig of same manufacture.
Then, can swig/sweat even more 'purchase' from the host line with the jig.
These (2Hand & swig) are 2 KEY principles to maximizing about any rope force i think (short of impact).
.
Over tighten ok on many things, then can give slack immediately as needed for greater range of control..
.



saveForces_6.png



sweatingToss-Adkins.JPG
 
Jonny said:
Originally made for rescue pickoffs and had a short rope on it. I put 300’ of 1/4” polyester double braid and now it’s a 7:1 for pulling leaning trees over. :)
View attachment 70189
Click to expand...
Nice!
300' of rope should give you 50' of pull when fully extended.
How does 1/4'' dia rope feel in the hands while pulling? I like the larger lines for this.
I have four sets of old school MA systems. They all have built in brakes and 3 are locking. The largest is a 200' x 5/8''D.
 
Reading the likes on the previous posts gave me remembrance of LimbLoppa. That guy would keep me laughing post after post while online.
I miss the guy.
 
I haven’t used it yet, so can’t say for sure, but I think it would suck to have to pull hard on it for very long. There’s a progress capture cam so it’ll maintain tension on its own, and then some little slip knots in the tail and gloves should make things a bit more comfortable. I could also whip up a little prusik loop with a scrap 3/4” “ handle on it for something more substantial to grip.
 
You must log in or register to reply here.

New threads New posts

Kask Stihl NORTHEASTERN Arborists Wesspur TreeStuff.com Teufelberger Westminster X-Rigging Teufelberger
Back
Top Bottom