The ascender is left-handed, as are virtually all chest ascenders that I have seen. The ascender is is 126 mm. high, 87 mm. wide, 38 mm. thick, and weighs 174 grams. The ascender shell is subtriangular shape bent from unfinished 4 mm. aluminum sheet. The rope channel is formed by bending the right side of the ascender into a U. The rope channel is 15.2 mm. in diameter. The main sling attachment point is located below the cam and behind the rope channel. A second attachment point lies above the cam, also behind the rope channel. The shell is bent backwards at both points to provide clearance between the attachment slings and the main rope. This accounts for the rather large thickness of this ascender. The attachment points appear to be circles distorts by the stamping operation. The lower attachment point measures 16 by 14.9 mm. and the upper 17 by 13 mm. A steel insert protects the lower hole from wear. The left end of the shell is bent on an inclined axis to form another U. A hole drilled through both sides of the U accepts a steel rivet. The cam and cam spring are mounted on this rivet, and a steel bushing protects the rear of the aluminum shell from having the rivet pull through. The pivot is centered 55 mm. from the inside of the rope groove.
The cam is a plated skeletonized steel casting. The cam radius, measured from the pivot, increases from 38 to 52 mm. over an angle of 44 degrees. The cam has number of small conical teeth, all of which have their axes approximately parallel to the lower surface of the cam. The tooth pattern is (2.3)(4.3)^5(2.3). A spring-loaded manual safety bar is mounted in the cam channel below the cam pivot. A cutout in the channel and a button on the safety allow one to reach it with thumb or finger. The normal action of the spring holds the safety against the cam channel. Swinging it in and down allows the cam to open fully. A hook on the cam safety can engage either of the two bottom tooth rows to hold the cam open.
The back of the shell is stamped "EMILSA."
Luc Bourguignon sent me this ascender in 2005, but it is probably much older. I do not have any information on its age or origin; in fact, I'm not even sure of the name. The "IL" in "EMILSA" stamped on the back of the ascender could also be read as "IX" or even as a "K;" however, Luc found some caving lamps by Emilsa which may be the same company.
The cam safety is both awkward an unique. Opening the ascender one-handed is quite difficult. When the cam hold-open is active, the aggressive hook makes releasing the cam more difficult than on most other designs.
The steel liner on the bottom attachment hole is not necessary, and it does present a sharp edge at one place on the back of the ascender. A tap with a hammer and a touch with a file should fix this.
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©2007, Gary D. Storrick