Support apparatus for medical appliance

A support apparatus for a medical appliance comprising support means having a vertical side surface and vertical guide means, lifter means adapted for mounting said medical appliance and positioned in said support means to be guided in vertical direction by said guide means, said lifter means having a vertical side surface adjacent to said vertical side surface of the support means, counterweight means, first pulley means provided on said support means at a level higher than said counterweight means for rotation about a horizontal axis, parallel link means including a plurality of parallel link arms each having one end pivotably connected with said lifter means and extending obliquely downward towards said vertical side surfaces of said support means, brake shoe means mounted on the other end of said parallel link arms and located between said vertical side surface of said lifter means and said vertical side surface of said support means, said brake shoe means having a friction surface facing the vertical side surface of said support means, a relatively small force spring means for biasing said brake shoe means upwardly with respect to said lifter means, second pulley means provided on said lifter means at a level below said brake shoe means for rotation about a horizontal axis, wire means having one end connected to said counterweight means and passing around and extending downwardly from said first pulley means and passing around said second pulley means and having its other end connected to the brake shoe means, such that normal tension in said wire means forces said brake shoe means in the downward direction against the biasing force of said spring means and causes the parallel link arms to be held downward so that the brake shoe means is maintained away from the vertical side surface of the support means and in abutting engagement with said vertical side surface of said lifter means, and such that decreased tension in said wire means permits the friction surface of the brake shoe means to be forced into contact with the vertical side surface of the support means under the biasing force of the relatively small force spring means, at which time said parallel link means allows the brake shoe means to be forced more tightly against the vertical side surface of the support means by the weight of the lifter means.