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I acquired my ISC Red from Patroller Supply in 2015.
My ISC Red is 97 mm. long, 104 mm. wide, 30 mm. high, and weighs 209 g. It consists of a movable lever and a fixed anvil sandwiched between two subtriangular plates made from 4 mm. anodized aluminum. A round 19 mm. eye is cut in the side of each plate. The front plate pivots on the lever mounting pin, and a notch in the left side of the front plate provides clearance for the anvil mounting pin.
The anvil and lever appear to be 13.5 mm. slices cut from an aluminum extrusion. The anvil is attached to the rear plate by two pins, one of which is extended to capture the notch in the front plate. The anvil itself is irregularly shaped with two humps. The lever is mounted on another rivet, but is free to rotate. A small spring forces the lever to the engaged position. A cutout on the rear side of the lever provides clearance for the spring. The distal end of the lever has a milled groove for the rope to ride in.
The side of the anvil opposite the rope has a small screw. A plastic "Popper™" (reminiscent of an old-style clothespin) engages this screy The other end has a 3 mm cord attached.
The front of the Red is printed with the Red logo, "I|S|C," "CE0120," a book-with-an-"i" icon, and two arrows labeled "UP." The rear is printed with "RP892," "EN12841:2006 A," "•Ø10.5-11mm EN1891:A," "Max rated load 140kg," "14/50381/192," two human icons, "Rescue 240kg," and "Complies with ANSI Z359.1 2007." The inside is stamped with the "Sieg Heil" icon.
The Popper™ allows the user to tow the Red downwards without the Red engaging. Unfortunately, it takes quite a bit of force to release the Popper™. I have my doubts but I haven't tested it. It is obvious, though, that the way mine was attached to the Red, it couldn't possibly work. I found an ISC brocure that shows a more reasonable rigging. Since I don't need a rope grab for caving, I’ll let others do the testing. Some already have, with less than favorable results.
Tests reported by the the US Bureau of Reclamation showed that the ISC Red does not always engage
It sometimes allows the user to drop the full length of the safety rope.
(Shaun Reed, Drop Testing of Rope Access Backup Devices, also see www.usbr.gov/rope/)
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I acquired my ISC Rocker in 2017 as part of Bob Thrun’s collection.
My ISC Rocker is 70 mm. long, 115 mm. wide, 29 mm. high, and weighs 168 g.
The rocker consists of a movable lever and a fixed anvil sandwiched between two plates. The rear plate is a diamond-shaped stamping made from 3.9 mm. anodized aluminum. A round 15.0 mm. hole is cut in the right side of the plate, and a larger 23.8 by 24.2 mm. hole is cut in the left side. The front plate is pear-shaped and smaller, lacking the projection for the upper hole. The front plate pivots on the lever mounting pin, and a notch in the left side of the front plate provides clearance for the anvil mounting pin.
The anvil and lever appear to be 14 mm. slices cut from an aluminum extrusion and subsequently anodized. The anvil is attached to the rear plate by a round-head stainless-steel bolt that threads into a "nut" behind the rear plate. The "nut" is turned to form a rounded head; it has no flat surfaces for using a wrench. The bolt shaft is stepped, with an 8 mm. diameter for 4.6 mm. to engage the front plate notch, then 7 mm. where it passes through the anvil and rear plate to the "nut." A coiled pin through the rear shell keeps the anvil from turning. The anvil itself is shaped like a low, wide isoceles triangle, with a cutout opposite the lever end. The lever is mounted on a similar bolt, but is free to rotate. A small spring forces the lever to the engaged position. A cutout on the rear side of the lever provides clearance for the spring.
The front plate has "CE0120," "BEN353-2," "BEN358," a book-with-an-"i" icon, "Rocker," "I.S.C.u.k.," and "OØ 10.5 - 12.7mm" printed on the face. The inside of the rear plate has the "Sieg Heil" icon stamped between the hammer and anvil. The rear has "06-023233M" stamped in a dot matrix font.
The following rope grabs are all variations of the same basic design:
|Image||Rope Grab||Manufactured||Side Plates||Lever Locking Tab|
|ISC Rocker||2006 (?)||3.9 mm. Anodized Aluminum||Yes|
|NTR Rocker||2017 (?)||3.9 mm. Anodized Aluminum||Yes
with forward fold
|Proverti AC080||4/2015||4.4 mm. Anodized Aluminum||Yes|
|Proverti AC081||4/2015||2.5 mm Stainless Steel||Yes|
|Singing Rock Locker||1/2008||4.0 mm. Anodized Aluminum||Yes|
|Troll Rocker, Version A||~2001||4.3 mm. Anodized Aluminum||No|
|Troll Rocker, Version B||~2003||3.9 mm. Anodized Aluminum||Yes|
|Vento (Венто) Rocker||~2019||3.9 mm. Anodized Aluminum||Yes|
|Xinda Rocker||~2014||4.0 mm. Anodized Aluminum||Yes|
|Vertical (Вертикаль) Rocker
|12/2021||4.0 mm. Anodized Aluminum||Yes
with forward fold
|Yates Rocker||~2003||4.3 mm. Anodized Aluminum||Yes|
|Z&W Rocker||~2019||4.0 mm. Anodized Aluminum||Yes
with forward fold
Each of these is a compact, lightweight (except for the stainless steel Proverti AC081) fall arrest that can also be used as a ratchet when hauling loads over a pulley. They can all be used as rocker-arm ascenders, but that was not the original design intent for the Troll Rocker, the progenitor of the others in the chart.
These have no sharp teeth to cut the rope sheath. Some informal testing suggests that, lacking teeth, these can slide before engaging, but normally the slippage is less than a foot. The cases where I observed this were somewhat contrived (i.e., I held the grab in a specific position and carefully dropped the load straight down), and so I'm not too worried about the slippage. I would be far more concerned if they had sharp teeth and didn't slip at all.
The top hole is used for releasing or offloading a locked rocker by placing a carabiner in the hole and pulling toward the slack rope.
Except for the early Troll, each of these incorporates a lever lock. Troll added one to theirs before the others came out. The lever lock works, but one needs to be careful not to bump it so that it accidentally disengages. A carabiner in the upper hole can help prevent this. When the lever lock is disengaged, it blocks access to the upper hole.
The NTR, Vertical, and Z&W have a forward 90° bend at the top of their lever lock, making their locks much easier to operate than the others that rely on shallow rounded serrations.
Troll warns that using a rocker as a on soft
or loose-sheathed ropes can cause the rope sheath to slip or tear. They also warn that rope conditions (water, ice, mud, dirt, etc) as well as rope diameter, manufacturer, etc. will affect device performance. These warning apply to all of these fall arrests.
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