Boat lift

Claim 1

A lift mechanism comprising in combination support means fixedly anchored adjacent a seawall; guide rail means having a first and second end and supported by said support means at said first end thereof; said guide rail means extending at an angle from said support means into a body of water retained by said seawall and anchored at said second end into the bed of the body of water; slider rail means having a first and second end and positioned in parallel relation to said guide rail means, guide means secured to said first and second ends of said slider rail means for slideably guiding said slider rail means relative to said guide rail means; friction reducing means positioned between said slider rail means and said guide rail means; lifter beam means angularly secured to said slider rail means at said second end of said slider rail means; said lifter beam means presenting a horizontal supporting surface; bunk means fixedly attached to said lifter beam means and screwdrive means operatively connected to said slider rail means whereby actuation of said screwdrive means will raise or lower said slider rail means, said lift beam means and said bunk means depending upon the direction of rotation of said screwdrive means; said guide means at said first end of said slider rail means including a pair of J-clamps having a short leg and a long leg with said long leg fixedly secured to opposite sides of said slider rail means and said short leg extending under a portion of said guide rail means; said friction reducing means including friction reducing wear strips attached to said first and second end of said slider rail means and also said short leg of said J-clamp to prevent metal to metal contact between said guide rail means and said slider means and also said J-clamps; said guide means further includes spacer means attached to the inner face of said long legs of said J-clamps to prevent said J-clamps from making metal to metal contact with said guide rail means; said screwdrive means including motor means operatively connected to a worm gear assembly the output of which is a rotary transport screw; thrust bearing means supporting said transport screw and transport carrier means attached to said upper end of said slider rail means; said screwdrive means further includes a transport screw guide; said transport screw guide being fixedly attached to said slider rail means in offset relation thereto and enclosing said transport screw along the entire length of said slider rail means; said thrust bearing means includes a supporting member fixedly attached to said first end of said guide rail means, a pair or thrust bearings mounted on said transport screw on opposite sides of said supporting member and a pair of adjuster nuts mounted on said transport screw outboard of said pair of thrust bearings; said transport carrier means converts the rotary motion of said rotary transport screw into longitudinal movement of said slider rail means and said lifter beam means.