Supporting apparatus for movably supporting an attachment apparatus relative to a basic apparatus

Claim 1

A supporting apparatus for movably supporting an attachment apparatus relative to a basic apparatus, said supporting apparatus comprising: a vertical shaft for swivelably supporting said attachment apparatus around the axis of said vertical shaft, said shaft having a bottom portion; holder means, mounted on said basic apparatus, for holding said vertical shaft in such a manner that said vertical shaft is vertically movable along said axis thereof; an operation member for vertically shifting said vertical shaft between an engaging position and a release position; a pivot pin provided at the bottom portion of the vertical shaft and having and engaging end to be engaged with said operation member, said engaging end being formed in a hemispheric shape to provide substantially a pin contact with the operation member; and swivel positioning means for positioning said attachment apparatus to a desired position around said axis of said vertical shaft; said swivel positioning means including an engaging pin member which is fixed to said vertical shaft and extends along the radial direction of said axis of the vertical shaft, and a plurality of engaging recess portions which are formed on a top edge of said holder means and are arranged in a circular form around said axis of said vertical shaft so as to face said engaging pin member in such a manner that said engaging pin member is selectively engageable with said engaging recess portions when said vertical shaft is held in the engaging position, thereby enabling the swivel positioning means to lock the vertical shaft to positively prevent the attachment apparatus from swiveling; and said swivel positioning means being disabled when said vertical shaft is shifted by said operation member to the release position from the engaging position, thereby allowing the vertical shaft to freely rotate around the axis of the vertical shaft to swivel the attachment apparatus.