Reversible transmission mechanism

A reversible transmission mechanism comprising an input member rotatable about a central axis and having a bevel gear, a first shaft member rotatable about central axis and having a shaft portion extending perpendicular to central axis, a second shaft member rotatable about central axis and rotationally fixed to said first shaft member, an output member rotatably mounted around said second shaft member and having a bevel gear at a first end thereof axially facing the bevel gear of said input member, a planetary bevel gear rotatably mounted around said shaft portion of said first shaft member so as to mesh with said bevel gears of said input and output members, a clutch for selectively coupling and uncoupling said second shaft member to and from said output member, and a brake for stopping rotation of said second shaft member while said second shaft member is uncoupled from said output member, whereby said output member is rotated in the same direction as said input member while said output member is coupled to said second shaft member through said clutch, and is rotated in a direction opposite to the direction in which said input member is rotated while said output member is uncoupled from said second shaft member.