SYMPOSIA PAPER Published: 01 January 1993

A New Mechanical Ski Binding with Heel Release Activated by the Bending Moment at the Boot Sole


This article describes a design concept for a new mechanical ski binding where heel release is activated exclusively by the anterior/posterior bending moment at the boot sole rather than the upwards force at the boot heel. This moment possibly correlates more strongly to the bending moment at the site of boot-top fractures than the upwards heel force. To gain this performance, the boot is forced to pivot about an axis transverse to the ski and directly beneath the ankle joint. A motion transformer converts vertical motion of the AFD into horizontal motion resisted by compression springs. Inasmuch as heel release is controlled by the degree of motion, adjusting the spring compression adjusts the release level. To activate release of the heelpiece, a Marker M40 binding, which rotates with the boot about the pivot, was modified by replacing the “Sensomatic” mechanism. The modification consists of a specially designed multi-link trigger mechanism that enables the binding to be unlatched without forcibly overcoming the spring force. This mechanism enables a force of 0.5N to activate release when the upwards force on the heel cup is 1000N (forward lean bending moment ∼270 Nm). Despite the incorporation of this trigger mechanism, the vertical elasticity, longitudinal compliance, and adjustability to different boot sole lengths are preserved. To demonstrate the workability of the concept, a prototype was constructed and tested successfully. With the workability of the concept proven, the development of a skiable prototype appears to be a worthwhile next step.

Author Information

Caldwell, B
University of California, Davis, CA
Landry, D
University of California, Davis, CA
Hull, ML
University of California, Davis, CA
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Developed by Committee: F27
Pages: 189–199
DOI: 10.1520/STP25570S
ISBN-EB: 978-0-8031-5237-3
ISBN-13: 978-0-8031-1494-4