Next Return Previous

International Safety Components Big Wall

Version A Version B RP240
Version A Version B RP240

Overview


Version A
(#145, 2211)

Front View: Closed Rear View: Closed
Front View: Closed Rear View: Closed
 
Front View: Open for Rigging Rear View: Open for Rigging
Front View: Open for Rigging Rear View: Open for Rigging

Technical Details

I acquired this pair of ascenders from Mountain Tools in 1999. I acquired another pair in 2017 as part of Bob Thrun's collection.

The shell is milled from a custom aluminum extrusion and hard-coated. The extrusion and overall rounded shape of the ascender are similar to the S.R.T. A1 Explorer. Like the S.R.T. (and the C.M.I.), the extrusion direction is oriented parallel to the vertical axis of the ascender, and contains two opposing channels. One channel is rounded and becomes the rope channel., the other is square and holds the cam. The angled hand hole is roomy, and a rubberized plastic grip with aluminum insets is riveted to the frame. A 20 mm hole is drilled at the bottom and a 16.2 by 20 mm. hole is milled through both sides of the rope channel. The hand hole is made a little wider than on the C.M.I. 5000 , so the rope channel barely protrudes from the ascender body as on the C.M.I. 5000 series and S.R.T. Caver/climber series.

The cam is a plated skeletonized, reinforced stainless steel casting with a (4.3)^6(4) conical tooth count. The tooth axes are perpendicular to the cam face. The teeth are well-formed except that the top inner tooth on my right ascender is missing. The cam, cam spring, and a cam housing are mounted on a 5 mm. roll rivet. The cam housing is a piece of thin sheet metal bent to cover the top of the cam channel and serve as a spacer along the sides of the cam. The top of the housing is flat instead of indented (compare it with the S.R.T. Caver/climber series). The cam safety is a spring-loaded piece of 3 mm. red anodized aluminum mounted on a 3 mm. stainless steel rivet placed through two tabs on the base of the cam. A small thumb knob is staked to the safety. The knob is turned to give a contoured grip. The safety is placed so that it does not interfere with one's hand in the handle.

The back of the frame is stamped "BATCH No 00532." The aluminum inset on the front side of the grip is marked with an arrow pointing up, "ISC UK" and "0120CE." The rear inset is marked "ØROPE MIN 9mm - 13mm MAX."

Comments

The I.S.C. is a very well made ascender. My first impression was "Wow!, this is a solid ascender." I have not broken an I.S.C. ascender, but the frame is undoubtedly very strong. It certainly won't have the "bending over the lip" problem that stamped-frame ascenders have. Perhaps it is too strong, because this is a very heavy ascender - only Version B and the nearly identical PMI Puma outweigh it. The hard coat finish is a nice touch, and the ascender should resist wear very well.

The sling attachment holes could use some more beveling. The sling attachment holes could theoretically have the same safety problem described for the Clog ascender, so I don't recommend using carabiners in them. The upper frame is still more difficult to grasp from above than either the Jumar or the small C.M.I. UltrAscender. This latter point is more important than having an upper attachment hole available.

The cam is very well made, reminiscent of Jumar's. I suspect that it is also quite strong. I'm not thrilled with semi-tubular rivets for cam pivots. I.S.C. should consider using a grooved pin and external retaining ring similar to the C.M.I. design. The cam housing is lightweight and crude, but it doesn't serve any critical function so I'm not too concerned with its design. If you want, take a hammer and dent the housing to limit the cam's closing so that the teeth do not hit the inside of the rope channel. It may even be possible to eliminate the cam housing completely and substitute two washers, or even widen the cam a bit and eliminate them too. The main drawback is that the cam housing helps keep mud out of the cam pivot, and eliminating the housing might cause the ascender to jam more easily in muddy conditions.

The ascender cam can be opened by either hand. The cam safety can easily be operated with the thumb of the normal hand (right hand for right-hand ascender), and the cam opened in one smooth motion. Opening with the opposite hand is easily done with the index finger, but the sharp end of the cam safety spring will most likely puncture the skin at the tip of the finger. The safety is the only part of the ascender that appears flimsy, and although I suspect it will hold up well, the one on the is S.R.T. A1 Explorer better. I've seen too many broken plastic ones on other ascenders to enjoy that technological "improvement." The safety can be hooked over the cam channel to hold the cam completely open. There is no partial cam hold open feature, nor is one needed.

In general, this is a very well made, rugged ascender which is suitable for a wide variety of uses. Too bad the weight wasn't cut in half.


Version B
(#287)

Front View: Closed Rear View: Closed
Front View: Closed Rear View: Closed
 
Front View: Open for Rigging Rear View: Open for Rigging
Front View: Open for Rigging Rear View: Open for Rigging

Technical Details

I acquired a left-handed Version B new on eBay from Michael McGuinn in 2009.

This is essentially the same as the P.M.I. Puma and Yates ascenders (the right ascender in the photographs is a Yates ascender). My Version B is 218 mm. tall, 82 mm. wide, 32 mm. thick, and weighs 369 g. The shell is milled from a custom aluminum extrusion and hard-coated. The extrusion and overall rounded shape of the ascender are similar to the S.R.T. A1 Explorer. Like the S.R.T. (and the C.M.I.), the extrusion direction is oriented parallel to the vertical axis of the ascender, and contains two opposing channels. One channel is rounded and becomes the rope channel; the other is square and holds the cam. The rope channel is 15 mm. wide. The angled hand hole is roomy, and a rubberized plastic grip with aluminum insets is riveted to the frame. A 20 mm. hole and a 13.5 mm. hole are drilled at the bottom and a 16.2 by 20 mm. hole is milled through both sides of the rope channel. The hand hole is made a little wider than on the C.M.I. 5000 , so the rope channel barely protrudes from the ascender body as on the C.M.I. 5000 series and S.R.T. Caver/climber series.

The cam is a plated skeletonized, reinforced stainless steel casting with a (4.3)^6(4) conical tooth count. The cam radius increases from 45 to 62 mm. over an angle of 41°, giving a 24° cam angle. The tooth axes are perpendicular to the cam face. The teeth are well-formed. The cam, cam spring, and a cam housing are mounted on a 5 mm. semi-tubular rivet. The cam housing is a piece of thin sheet metal bent to cover the top of the cam channel and serve as a spacer along the sides of the cam. The top of the housing is flat instead of indented (compare it with the S.R.T. Caver/climber series). The cam safety is a spring-loaded piece of 3 mm. red anodized aluminum mounted on a 3 mm. stainless steel rivet placed through two tabs on the base of the cam. A small thumb knob is staked to the safety. The knob is turned to give a contoured grip. The safety is placed so that it does not interfere with one's hand in the handle.

The front of the rope channel has a milled up-pointing arrow. The back of the frame is stamped "07/210/3784" in dot-matrix font. The aluminum inset on the front side of the grip is marked with an arrow pointing up, an ISC logo, and "0120CE." The rear inset is marked "ø ROPE MIN9mm-13mm MAX."

Comments

Since this is essentially the same as the P.M.I. Puma and Yates ascenders, my comments on them apply to this one as well. The up-pointing arrow is unnecessary, but does no harm. I find it curious that two essentially identical ascenders from the same company have labels indicating that they fit different size ropes.


RP240
(#2024, 2209)

Front View: Closed Rear View: Closed
Front View: Closed Rear View: Closed
 
Front View: Open for Rigging Rear View: Open for Rigging
Front View: Open for Rigging Rear View: Open for Rigging

Technical Details

I acquired a right-hand International Safety Components RP240 from Aarond Reagan in 2015. I acquired a pair in 2017 as part of Bob Thrun's collection.

The RP240 is 217 mm. tall, 84 mm. wide, 35 mm. thick, and weighs 365 g. It is essentially the same as Version B with the addition of a safety pin that keeps the cam from opening far enough to let the rope release. The 4.85 mm. in diameter and 35.3 mm. long, and has a spring-loaded ball to secure it in a 5 mm. hole drilled below the cam axle. A 1.5 mm. plastic-covered stainless steel cable connects the pin to a hole in the shell, above the hand grip.

The shell is milled from a custom aluminum extrusion and hard-coated. The extrusion and overall rounded shape of the ascender are similar to the S.R.T. A1 Explorer. Like the S.R.T. (and the C.M.I.), the extrusion direction is oriented parallel to the vertical axis of the ascender, and contains two opposing channels. One channel is rounded and becomes the rope channel; the other is square and holds the cam. The rope channel is 15 mm. wide. The angled hand hole is roomy, and a rubberized plastic grip with aluminum insets is riveted to the frame. A 20 mm. hole and a 13.5 mm. hole are drilled at the bottom and a 16.2 by 20 mm. hole is milled through both sides of the rope channel. The hand hole is made a little wider than on the C.M.I. 5000 , so the rope channel barely protrudes from the ascender body as on the C.M.I. 5000 series and S.R.T. Caver/climber series.

The front of the rope channel has a milled up-pointing arrow. The back of the frame is stamped with "I|S|C," "0123CE", "ROPE Ø:MIN 9mm - 13mm MAX," "RP240," and "10/13237/01."

Comments

CMI once offered a similar safety for their Shorti ascenders. As I noted then, this type of safety pin substantially reduces the chance of the cam opening accidentally. It does not interfere with the normal safety, so both must be overridden for the cam to open. Using the safety pin adds extra steps to common procedures such as passing knots or rebelays, so I prefer not to have it.