Blocks\Pulleys General info

[goodwood613]

I need to get a few blocks/pulleys mainly for rigging so I don't wreck my ropes using natural crotches and mechanical advantage for pulling over stalks. I have a few general questions....for instance what is the difference between a block and a pulley? Anything? What is the number as far a tonnage that they give you ie 2 tons, 4 tons. I don't plan on rigging anything nearly that big. Any one have any good suggestions on a multiuse block/pulley? I usually order from sherrill tree so if you have any ideas on products they carry that would be great. Thank you for your time and knowledge.

 

[sgreanbeans]

Get the book "the art and science of practical rigging" by Arbormaster. Will educate you on the subject. Don't do any type of advanced rigging unless you have a clear understanding of it. Pulleys connect with a link, blocks with rope

 

[treeslayer]

To me, pulleys merely redirect a rope, a block carries the load and the heat. use a block in the tree, pulleys on the ground.....:msp_thumbup:

 

[treeslayer]

Get the book "the art and science of practical rigging" by Arbormaster. Will educate you on the subject. Don't do any type of advanced rigging unless you have a clear understanding of it.

you don't think you can load a 2 ton block, you better read this book.....:hmm3grin2orange:

 

[Saw Dust Smoken]

Pulley or block

Pulley can be used up in tree or on ground. Not designed to be shock loaded. Pretension the load. You will notice pulleys have more sharp edges in the metal frame.
Block are designed for shock load in action. Smoother edges in metal frame build.
Either of these can be rated for the same weight. But are designed for a different syle of use!

 

[TreeGuyHR]

Pulley can be used up in tree or on ground. Not designed to be shock loaded. Pretension the load. You will notice pulleys have more sharp edges in the metal frame.
Block are designed for shock load in action. Smoother edges in metal frame build.
Either of these can be rated for the same weight. But are designed for a different syle of use!

Learned the hard way on that one. I had an assortment of gear on hand, but my climber used a pulley to rig a 30 ft. top, and the lowering line snagged on the casing and the rope attaching the pulley to the tree snapped -- had to replace a section of wooden fence when the top flattened it, as well as retire the lowering line because of rubbing on the casing and shock loading (now used as just a tag line). He didn't bother using my heavy block, which would not have snagged the load line.

Which raises another point -- any rigging is only as strong as the weakest link; in this case, a little scrap of rope that my climber liked, a piece of his personal gear. After that, he only uses my official, heavy rigging loops or short hanks of 5/8 or 7/8 rope.

OTH, it might have been a good thing that the gear failed, or the tree would have shock loaded even more than it did :msp_ohmy:.

It was a good teaching moment.

 

[squad143]

I have a few general questions....for instance what is the difference between a block and a pulley? Anything? What is the number as far a tonnage that they give you ie 2 tons, 4 tons.

A picture is worth a thousand words, or so the saying goes. I guess a video is worth more.

These two videos help explain the difference. However, in the second video, they show the rope connected to the becket directly. Don't do this, attach it via a biner. I believed they were only showing it for demonstration purposes.

Rigging Blocks and Pulleys Part 1 - YouTube

Rigging Blocks and Pulleys Part 2 - YouTube

Any one have any good suggestions on a multiuse block/pulley? I usually order from sherrill tree so if you have any ideas on products they carry that would be great.

I purchased this kit from Sherrills a few years ago (only difference was they used the gold Petzl pulleys) and have been quite happly with it:
Mechanical Advantage Tree Pulling Kit by SherrillTree & Petzl, 9/16" capacity | SherrillTree.com

Or you may want to consider this kit: Fiddle Block Kit | SherrillTree.com

One advantage to the fiddle block kit, is that it is easier to use with a lowering device (port-a-wrap).
The advantage to the other kit, is it is easier to seperate and use the pulleys for other uses, such as re-directs.

I have, on occasion, used a block as a pulley (re-directs).
I would never use a pulley as a block.

 

[lumberjack333]

Pretty sure a block runs on bushings, capable of handling a shock load. Pulleys run on ball bearings, nice and smooth - but won't take the shock well at all. Time to dig into the library and do some reading...

 

[Mikecutstrees]

Best all around block in my experience has been a CMI 5/8" stainless block. Excellent block. I usually use a 12' 5/8 tail on it. Strong lightweight and good all around block.

Mike

 

[rbtree]

Pretty sure a block runs on bushings, capable of handling a shock load. Pulleys run on ball bearings, nice and smooth - but won't take the shock well at all. Time to dig into the library and do some reading...

Incorrect.

I own several CMI pulleys, which can be had with either a bushing or bearing. A bushing will hold up better in dirty gritty conditions, and can raise the rating of the pulley, as you noted.

The main difference was posted a bit above, which is that the attachment point of a pulley is simply made via a hole in each cheek plate.

A block has a pin and sheave, allowing it to be attached to an eye sling, as opposed to a shackle or carabiner, in the case of a pulley. Shock loading a pulley with a load can easily damage the cheek plates.

 

[TreeGuyHR]

Incorrect.

I own several CMI pulleys, which can be had with either a bushing or bearing. A bushing will hold up better in dirty gritty conditions, and can raise the rating of the pulley, as you noted.

The main difference was posted a bit above, which is that the attachment point of a pulley is simply made via a hole in each cheek plate.

A block has a pin and sheave, allowing it to be attached to an eye sling, as opposed to a shackle or carabiner, in the case of a pulley. Shock loading a pulley with a load can easily damage the cheek plates.

good post.

I have a couple CMI pulleys (MBS 16,000 lbs) and a CMI block (MBS 40,000 lbs, SWL 6,000, max 3/4 rope). I love the block; has a roughened round "nut" that can be loosened when up the tree to attach a loop. The pulley that was shock loaded was attached with a steel 'biner, and the inside of the holes in the plates got flattened out a bit -- wonder if i should retire it?

 

[TreeGuyHR]

Couple pics:

First two are of the CMI MBS 16,000 lb pulley, second showing flattening in rigging hole; third pic of the CMI 40,000 MBS block

View attachment 279592View attachment 279593View attachment 279594

 

[nelson727]

Original post - goodwood613 , my experience has always been that I ran out of money long before I ran out of tree gear I was interested in buying. Wanted to make sure you were aware of X Rigging Rings as another option for some things. Blocks have their place, pulleys theirs. Go to Youtube and enter, X Rigging Rings, to see what XRR’s can do for you. Google same and you can find some written info..

Link at top of page to Treestuff.com has pictures etc..

 

[ForTheArborist]

I need to get a few blocks/pulleys mainly for rigging so I don't wreck my ropes using natural crotches and mechanical advantage for pulling over stalks. I have a few general questions....for instance what is the difference between a block and a pulley? Anything? What is the number as far a tonnage that they give you ie 2 tons, 4 tons. I don't plan on rigging anything nearly that big. Any one have any good suggestions on a multiuse block/pulley? I usually order from sherrill tree so if you have any ideas on products they carry that would be great. Thank you for your time and knowledge.

No tree service runs without ample blocks and tackle. You'd just be dangerously crazy and wasting your time without this stuff.

Something interesting to add to this topic are the concepts of floating rigging blocks. DMM makes some interesting gear for highly technical rigging that 99% of the climbers understand. One of their devices is the DMM Hub for 3D rigging in thin air instead of immediately off the tree,. They have have some amazing blocks too. Google it or search on Youtube.

Good luck out there.

 

[cjtreeclimber]

I’d love to step it up with getting a good block and larger rigging line so I can start blocking down peace’s weighing way over 1,400 work load. I use a loopy sling, which I simply girth hitch around a strong limb and hook my pulley on with a heavy duty carabiner. Seems like a fast working set up. If I had the black I’d have to keep it attached and cow hitch it to everything. My rigging rope stays in the pulley with another carabineer attached with an anchor hitch. Any time I have to shock load something I tell my ground guy to let the load run slightly at first to try to absorb the shock. Hardly ever rig off peace’s of tree trunks because I get mostly cheapie craigs list jobs with no grass to worry about so that’s all cut and chuck or felling down from there . . .
[video=youtube;Vs64Uai6z88]https://www.youtube.com/watch?v=Vs64Uai6z88[/video]

 

[lumberjack333]

Incorrect.

I own several CMI pulleys, which can be had with either a bushing or bearing. A bushing will hold up better in dirty gritty conditions, and can raise the rating of the pulley, as you noted.

The main difference was posted a bit above, which is that the attachment point of a pulley is simply made via a hole in each cheek plate.

A block has a pin and sheave, allowing it to be attached to an eye sling, as opposed to a shackle or carabiner, in the case of a pulley. Shock loading a pulley with a load can easily damage the cheek plates.

Noted, thanks for the correction.