CMI ropejack

Jehinten

Jehinten

Been here much more than a while
Location
Evansville
I've owned a rope jack for probably 7 years now. Great piece of equipment for a quick mechanical pull especially if your mini skid is already busy with another task or if you need it up in the tree.

After several years of use, my handle was slightly bent which didn't affect its use and finally, a bushing wore out where the ascender is bolted to the handle and eventually caused one of the ascenders to break free from the handle. Due to the design of the tool, the other ascender held the load.
I contacted CMI about replacement parts to rebuild it and they suggested that I return it to them for inspection and repair as the bushings have to be pressed in. I shipped it in on the 6th and received a brand new ropejack today on the 18th.

They didn't ask for a proof of purchase, send me back to the retailer or tell me that I exceeded the expected life of the tool, all of which would have been reasonable answers.

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southsoundtree said:
What is the benefit of a rope jack compared to/ over other MA systems?
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For me, it's light weight and more versatile than a masdaam which it is most closely related to out of the different MA systems.

Due to the design it is midline attachable, so you can use it on multiple ropes in a single rigging senerio. Tension one and lock it off on a POW, figure 8.... then take the ropejack off and move it to another rope.

The one rope it doesn't work great on is 3 strand ropes. All other arborist ropes that ive tried work well.

As for block&tackle systems, it's easier/faster to deploy as well as lighter and tangle free.



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CMI says it's about 3:1 MA, and is more challenging to get off of lines fatter than 13-14mm, so you can lose some speed there. I like it in principle, and still wanna get one.
 
I keep a high-strength, 25-30’ 10mm line, hitch cord, and biner with mine. For bigger pulls, I add a hitch cord, micro pulley and biner.

Tie the line around the anchor tree above the portawrap, attach the hitch cord to the line, and clip the rope Jack to the hitch cord with the biner.

Use the portawrap to capture the main line, and attach the small line to the host line using a Blake’s. Then put the small line in the rope jack, with a little slack between the hitch cord and ascender.

This way the teeth are never on the main line, and when you’re finished tensioning, capture any slack in the main line with the portawrap. Then slide the hitch cord attached to the rope jack to take pressure off the cams. If you need to multiply force, attach the hitch and pulley to the main line, run the small line through the pulley and back to the rope jack- 2:1 multiplier to the rope jack advantage. One day I might remember to photo the setup. It’s soooooo much easier to take the rope jack off of pull lines.
 
Matias said:
CMI says it's about 3:1 MA, and is more challenging to get off of lines fatter than 13-14mm, so you can lose some speed there. I like it in principle, and still wanna get one.
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I wouldn't use it on lines bigger than 1/2" (13mm) if I need a larger line than that I'll use a winch for more power.

Taking it off of the line is only an issue when you need to take it off of a tensioned line with nothing to transfer the tension over to. With a Porta wrap to lock the main line off you can get the ropejack off of the line in 2-3 quick movements. If it's a pull for felling then it comes off immediately as the line is already slack.

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This is how I set mine up most of the time, assuming the rope is long enough I will use the same rope for the anchor and pull. The only additional hardware is a carabiner to attach the ropejack.

If a portawrap is involved, I just carabiner to the top loop on the POW.
42408529e157be7e4851f3974270a535.jpg


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Jehinten said:
This is how I set mine up most of the time, assuming the rope is long enough I will use the same rope for the anchor and pull. The only additional hardware is a carabiner to attach the ropejack.

If a portawrap is involved, I just carabiner to the top loop on the POW.
42408529e157be7e4851f3974270a535.jpg


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What is a painter's bowline? How is it different from a regular bowline?
 
Dan Thornton said:
What is a painter's bowline? How is it different from a regular bowline?
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It's a variation that is very similar to a regular bowline, but is midline. I first heard of it here on treebuzz while discussing a few bowline variations, I cannot find an example with a Google search, so I've edited a bowline example.

Basically create your loop as normal, but midline instead of near the end. Then tie as normal with a bight instead of the end. I prefer to clip into both loops that are created
f0bbd85841f9286dfdbd73264beb6f0c.jpg


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A cleaner example can be found here.

This knot must have a name . . .

The photo shows what I've always called a bowline with a bight, to show that it's different than a bowline on a bight. I tried to find it in Ashley's Book of Knots (ABOK), but haven't found it. I've used it a lot and never had it fail or be difficult to untie. I've never used it with the...
www.treebuzz.com

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Good use of it for sure, and I see how and where it can be used quickly and easily in a number of other situations as well. That said, even in a 2-1 pull, it's still not as much force as a Maasdam Rope Puller (my favorite pulling device) at 1,500 pounds, and may only be closer to 1/3-1/2 as a Maasdam single line pull as the CMI in a double-line. I've got like... 5 different pulling devices but not one of these, I should probably get one for that twice a year situation I'd use it....

https://www.wesspur.com/RIG234-cmi-rope-jack
Testing has shown that a single person can generate somewhere between 300-80O pounds of force while using the Rope Jack
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27RMT0N said:
Good use of it for sure, and I see how and where it can be used quickly and easily in a number of other situations as well. That said, even in a 2-1 pull, it's still not as much force as a Maasdam Rope Puller (my favorite pulling device) at 1,500 pounds, and may only be closer to 1/3-1/2 as a Maasdam single line pull as the CMI in a double-line. I've got like... 5 different pulling devices but not one of these, I should probably get one for that twice a year situation I'd use it....
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I'm curious who did the testing. Info on the amount of pull seems to vary with each source. CMI has it listed as a 3:1, Wesspur and treestuff has it at 5:1.


I don't have any numbers, but I've seen what it's capable of. Granted I haven't used a masdaam, but I have used a come-a-long. Using the ropejack, I've broken larger (granted already crispy) Ash tops to avoid other canopies when felling. Probably 12" diameter where it broke in a single line pull. Another time I can think of, I preset tension before felling an oak. Pulled a 4:1 with the ropejack until the rear-end of the pickup that I was using as an anchor started sliding sideways (it was parked 90° from the pull to avoid blocking a one lane road)

Certainly not the best tool for everything, but it is a good tool for its size/weight.

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Different tools for different situations for sure.

The manufacturer (or at least the Wesspur site) says ""NOT for heavy loads" and I believe that when it says "Testing revealed CMI ascenders will strip the sheath of brand new 1/2" rope at roughly 1500lbs)" which is obviously a result of it being a cammed device rather than the much larger bend-radius ratchet wheel of the Maasdam. I really doubt a person could make that much force by hand, as supported by their ballpark numbers for force, so not really an issue. I've had a Maasdam slip an inch here or there with well worn wheels or ropes, but never once been worried about damaging the rope, even with what I'd consider pretty heavy loads and pushing it to the limits.

For something like a light-weight, midline attachable lifting device used in a tree here and there it seems great, a lot less fuss than the spaghettis of a 5:1 pully if you don't have to make long travel, repeated pulls. I feel like there are better options for pulling over trees or sticks though.
 
27RMT0N said:
Different tools for different situations for sure.

The manufacturer (or at least the Wesspur site) says ""NOT for heavy loads" and I believe that when it says "Testing revealed CMI ascenders will strip the sheath of brand new 1/2" rope at roughly 1500lbs)" which is obviously a result of it being a cammed device rather than the much larger bend-radius ratchet wheel of the Maasdam. I really doubt a person could make that much force by hand, as supported by their ballpark numbers for force, so not really an issue. I've had a Maasdam slip an inch here or there with well worn wheels or ropes, but never once been worried about damaging the rope, even with what I'd consider pretty heavy loads and pushing it to the limits.

For something like a light-weight, midline attachable lifting device used in a tree here and there it seems great, a lot less fuss than the spaghettis of a 5:1 pully if you don't have to make long travel, repeated pulls. I feel like there are better options for pulling over trees or sticks though.
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I broke a masdam on a huge dead pine leaning over a highway. Thank God I always back up with knots as I go in case it slips. I literally sheared the hub and cracked the gear. Granted, it was well used and abused anyways, but I'm not that big. I still love them for convenience, but became very aware that they're not bomb proof.
 
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