Secured to spindle 1 by flat springs a are rods 2 along which balls 3 slide. The balls are suspended by coiled wires b from member 4 which can be lowered and raised in a slot in the thicker part of spindle 1. Member 4 is connected to tierod c which passes through the central hole in spindle 1 and is secured in the hole of regulating screw 5. Rods 2 mount brushes which, when forced against conical surface 6, have a braking effect.
$430$SL,G$