Inertia compensated step-in ski binding

An inertia compensated ski boot release device for a safety ski binding comprising:

• a support plate fixable mounted to a ski;
• a toe-cup assembly pivotably carried by the support plate on a first pair of vertical pivots;
• said toe cup assembly including a pair of laterally spaced toe cups which engage the boot toe;
• a two-link parallel motion mechanism, each link pivotably attached to the toe-cup assembly and to one of the first pair of pivots to allow lateral motion of the toe-cup assembly in an arc about the first pair of pivots without rotation of the toe-cup assembly;
• a balance member pivotally mounted on a vertical pivot attached to the support plate, and extending longitudinally of the ski between the links of the two-link parallel motion mechanism,
• spring means extending laterally between each link and the balance member and cooperating to center the balance member on the support plate and prevent movement of the toe-cup assembly until the moment generated by lateral boot force exceeds a spring preload;
• means for releasing the toe cups, allowing them to rotate outward, releasing the ski boot when the toe-cup assembly has reached the design limit of travel, said releasing means including:
• a stop on the forward end of the balance member,
• a set of links, pivotably attached to the toe cups, said links normally abutting against said stop on the balance member and preventing the toe cup from pivoting, said stop moving out of contact with the links at the limit of travel of the toe-cup assembly, to enable pivoting of the toe cup,
• a mass;
• means for slidably attaching the mass to the balance member on the opposite side of the second pivot from the toe-cup assembly to generate a moment about the second pivot, under the influence of lateral acceleration, that is equal and opposite to the moment generated by the boot mass to cancel the internal acceleration force generated by the boot mass.