BELT ROLLER HAVING SWITCHABLE SPRING DEVICE

摘要

PURPOSE: A belt winding roller is provided to simplify and ensure a constitution of a switching device for switching respective springs and to sufficiently ensure a returning to a winding spring by a force of comfortable spring even at the time of an inconvenient manufacture tolerance and a friction loss in a belt winding roller having a switchable spring device. CONSTITUTION: An effective winding spring is arranged between a housing part and a belt shaft for accommodating a belt band and a comfortable spring connected thereto in series through a claw wheel and having a weaker strength than that of the winding spring is provided. A speed-reduction transmission(23) equipped with a tooth segment for controlling a switch lever(28) for a switching between the winding spring and the comfortable spring is provided. At this time, a speed-reduction ratio of the speed-reduction transmission(23) is constituted such that the belt shaft rotation started with a drawing of the belt band causes a rotation of the tooth segment with a rotation less than complete one rotation until it arrives at a switch point to shield a winding spring(19).