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Handled Type 1 Lever Cam Ascenders

In elementary school science we all learned that a type 1 lever has the fulcrum between the load and the applied force, so it made sense for me to define a Type 1 Lever Cam Ascender as one where the pivot was between the sling and the rope.

Lever cam ascenders generally rely on the mechanical advantage of the lever arrangement to provide sufficient force to keep the cam from slipping. Specifically, the lever acts to provide a higher normal force between the cam face and the standing rope, so the friction generated parallel to the standing rope is sufficient to hold the load. As load is increased, the normal force increases, and so does the parallel frictional force. The cam teeth are secondary in importance to proper lever design, and so lever cam ascenders can often withstand severe tooth wear without losing their ability to hold a load.

The four ascenders listed here use the same design, i.e., a hinged frame to connect the lever to the sling rope. I've seen Czech ascenders that have a rigid frame where the sling rope passes through a tube in the handle and ties to the lever, but I haven't been able to obtain any of these for my collection. I believe these are noncommercial, since I did not't seen any of them in any of the Czech Sport shops during my many visits to that country (where the Budvar is excellent, and the Ceské Budéjovice women are gorgeous).

Gallery

Image ID Device Description Acquired Weight Height Width Thickness Std. volume
Black Diamond nForce 219
2106
Black Diamond nForce LH & RH, stamped pivoting frame, plastic grips, round top & bottom holes, lever cam, Z teeth, hold-open catch
  • Mountain Gear, 2007
  • Bob Thrun Collection, 2017
182 194 105 33 663
Kong-Bonaiti, Version A 55 Kong-Bonaiti, Version A LH & RH, stamped pivoting frame, plastic grips, round top & bottom holes, lever cam, Z teeth, hold-open catch Speleoshoppe, 1982 237 206 94 30 578
Kong-Bonaiti, Version B 56
1556
2107
Kong-Bonaiti, Version B LH & RH, stamped pivoting frame, plastic grips, round top & bottom holes, lever cam, sloping & Z teeth, hold-open catch /w removable safety extension
  • Speleoshoppe, 1985
  • Robert M. Blake, 2011
  • Bob Thrun Collection, 2017
263 206 95 30 587
Russian Copy of Kong-Bonaiti 58 Russian Copy of Kong-Bonaiti LH & RH, stamped pivoting frame, plastic grips, round top & bottom holes, lever cam, sloping & Z teeth, hold-open catch John E. Weinel, Inc., 1989 275 207 98 29 588