Patent ID: 7220205
Filing Date: 2007-05-22
Classification: F16H

Abstract:
1. An automatic speed reducing ratio-switching apparatus arranged between a rotary driving source and an actuator for automatically switching a speed reducing ratio for a displacement member operated by a rotary driving force of said rotary driving source, said apparatus comprising: a planetary gear mechanism including an input shaft which is connected to said rotary driving source, an output shaft which is connected to said actuator, a sun gear, planet gears, and an internal gear which are helical gears respectively, and a carrier which rotatably supports said planet gears and which is rotated integrally in accordance with revolution of said planet gears; a resistance element which generates a thrust force between said internal gear and said planet gears; and a braking mechanism which brakes rotary motion of said internal gear by moving said internal gear by said thrust force depending on increase or decrease in output load.