Patent ID: 8800947

Claim:
A stepped lowering device comprising: a lifting/lowering link having a first pivot on a base and a second pivot on an ascending/descending body; a toothed link which is pivoted on one of said base and said ascending/descending body via said first or said second pivot, includes a link ratchet positioned on a circular arc about said first or said second pivot, and swings in association with said lifting/lowering link; an input member, supported by the one of said ascending/descending body and said base that includes the first or the second pivot that serves as a center of said circular arc of said link ratchet, to be operated to swing between a neutral position and a down position; a first lowering prevention latch mechanism comprising a first latch, said first latch is engaged with said link ratchet to prevent said toothed link from swinging downward when said input member is in said neutral position and which allows said toothed link to swing downward when said input member is operated to swing in a lowering direction; and a second lowering prevention latch mechanism comprising a second latch, said second latch allows said toothed link, which is allowed to swing downward by said first lowering prevention latch mechanism, to swing downward by an amount corresponding to one tooth of said link ratchet, and which is engaged with said link ratchet to prevent said toothed link from further swinging downward.