The Crutch: Carrying the Body on the Hands

When a leg cannot bear weight, the arms must take it. Crutches are among the oldest aids there are, and their design is a question of mechanics: the load must go through the hands, not the armpit, and the tip must not slide. The underarm crutch braces against the side of the chest while the hands carry the body weight; leaning on the armpit pad instead compresses the nerves there. The tip's rubber grips only as long as the crutch is not planted too far out — the angle and the floor decide whether it holds. This rung works out the loads through the hands and the friction the tip needs, gives the standard fitting guide, and measures both on the bench.