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CMI Large UltrAscenders

Version A Version B Version C Version D
Version A Version B Version C Version D

Overview


Version A
(#31, 2229)

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 J. E. Weinel, Inc. in June, 1989. I acquired another pair in 2017 as part of Bob Thrun's collection.

Version A is 186 mm. tall, 78 mm. wide, 29 mm. thick, and weighs 267 g. The rope channel is 18 mm. wide. The cam radius increases from 41 to 57 mm. over an angle of 42°, giving a 25° cam angle. The tooth pattern is (4.3)^5(4).

This ascender uses the same frame extrusion design as the C.M.I. 5004. Several colors were available, mine is red and uses a non-epoxy paint. The remainder of the ascender has been extensively modified. The cam is a skeletonized steel forging(?). The conical teeth are oriented perpendicular to the cam face and are set in a (4.3)^3(4) pattern. The safety has been removed from the cam and is now located in the traditional Jumar position. The molded plastic cam safety has seven teeth which can engage the lower cam teeth, providing a number of positions for holding the cam partially open. Two checkered ears on the safety give one's thumb or finger something to reach to open the safety. A cutout between the two ears provides clearance for the cam to function. A roll pin holds the safety and safety spring in position. Below the safety is a hand grip assembly consisting of two black plastic pieces pinned to the frame with a single roll pin. The larger piece has three molded finger grooves, and a road shelf at the bottom to keep the little finger off the frame. The other piece is a spacer whose sole purpose appears to be so that the same hand grip molding could be used on both right and left hand ascenders.

Comments

This ascender has some major improvements over the C.M.I. 5000 series, but it has some disappointing features as well. The new safety location is a big improvement, since the old design was, to put it bluntly, abysmal. The new safety is vastly superior, but the execution of the new safety still leaves something to be desired. The ascender can be operated with both hands, but once the ears break off (and I have no doubt they will) there will be very little exposed safety left to reach. Even in its original condition, the ears are located too high and too close to the handle to be reached easily. The cutout between the ears is completely unnecessary, since there would be adequate room for the cam to operate even if this area were completely filled in. This would also strengthen the ears.

I do not like cam safeties which can hold a cam partially open. I can understand holding the cam full open while waiting for your turn on rope, for example, but partial hold-opens are next to useless. In fact, they present a potential hazard if the cam does not close completely when rigging in, particularly if the ascender is being used as a safety at the pit lip. My philosophy is simple: if an ascender is on rope, it should be capable of holding weight. Most situations where a hold-open are useful (e.g., rescue hauling systems) involve some form of ascender abuse.

The finger grooves on the hand grip are simply too small, and should be eliminated entirely. I have large hands and find them uncomfortable. In order to get some other opinions, I went out in search of petite women with small hands to see if the ascender fit their hands. To date I have found one man and one woman with small enough hands to fit the finger grooves. Furthermore, the shelf at the base of the hand grip serves no essential function, and simply reduces the usable size of the handle. Even without the shelf, the hand grip would keep the rope from jamming in the cam groove as noted above. Fortunately, both the finger grooves and the shelf can easily be filed off.

The paint is far less durable than on the C.M.I. 5004, and chips off very quickly.

The cam is much more strongly reinforced than the 5000 series cams, and the overall workmanship is excellent. I prefer cam teeth oriented either parallel to the top of the cam, or pointed downwards, because they tend to be self-cleaning, but there is really nothing wrong with teeth set perpendicular to the cam face.

Don't misunderstand these comments; most of them are related to minor considerations. I like the UltrAscender far more than the previous C.M.I. versions. The UltrAscender has an extremely strong frame, and although I haven't tested one to destruction, looking at the design, I suspect the cam strength is also very high. In general, this is a very usable ascender as manufactured and can be easily modified into an excellent ascender.


Version B
(#114)

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 my Version B from Inner Mountain Outfitters in 1995.

Version B is 186 mm. tall, 78 mm. wide, 29 mm. thick, and weighs 267 g. The rope channel is 18 mm. wide. The cam radius increases from 41 to 57 mm. over an angle of 42°, giving a 25° cam angle. The tooth pattern is (4.3)^5(4).

Comments

The only difference between Version A and Version B is that Version A has a plated stainless steel cam, and Version B has a dark steel cam. Functionally, they are identical.


Version C
(#216, 2230)

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 my Version C from Tetyana Zurigat in 2007. I acquired another pair in 2017 as part of Bob Thrun's collection.

Version C is 187 mm. tall, 78 mm. wide, 28 mm. thick, and weighs 263 g. The rope channel is 18 mm. wide. The cam radius increases from 41 to 57 mm. over an angle of 42°, giving a 25° cam angle. The tooth pattern is (4.3)^5(4).

The main difference between Version B and Version C is that Version C has a semi-tubular rivet for the cam axle instead of a solid pin held by an external retaining ring.

The rear of each frame is stamped with the Underwriters Laboratories "Classified" logo, "CMI," "P 9901," "Meets NFPA 1983 (95ed)," and "MBS 4600lb. 20.5 kN."

Comments

The semi-tubular rivet is a significant step backward, since it makes replacing a worn cam much more difficult. I've heard that this feature was a misguided attempt to reduce CMI's liability or to interfere with natural selection. I don't know for sure, but no one seems to sell replacement cams any more.

I'd like to make a small comment on the "MBS 4600lb. 20.5kN." line for the bigger-is-better crowd. In no way am I picking on CMI here, but this ascender provides a good illustration of a generic issue: the breaking strength of vertical equipment has almost nothing to do with how it is used. For example, probably no eccentric cam ascender can hold 20.5 kN on all ropes that it will grip, and I doubt that any can reliably do so even on ropes at the larger end of the range: the cams will damage the rope first. There is no question that the CMI UltrAscender is one of the stronger ones available, and that it has strength to spare for normal use, but "MBS 4600lb. 20.5kN." is misleading.


Version D
(#246)

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 my Version D from Inner Mountain Outfitters in 2008.

Version D is 186 mm. tall, 77 mm. wide, 27 mm. thick, and weighs 271 g. The rope channel is 18 mm. wide. The cam radius increases from 41 to 57 mm. over an angle of 42°, giving a 25° cam angle. The tooth pattern is (4.3)^5(4).

Version D has a metal safety. The safety on Version D has a smoother finish than the earlier ones, and it is missing the checkered surface on the safety's tabs. A thick layer of black paint covers the safety.

Version D does not have any stampings on the frame.

Comments

The safety design is similar to the earlier versions, so it is still somewhat awkward. The lack of checkering makes the safety more slippery than the older plastic ones, but at least the tabs should not break off as easily. It is a shame that CMI did not completely overhaul the safety design instead, so I did that myself.