Hemispherical shoe

Abstract

A semi-spherical shoe 1 has a convex semi-spherical surface 1 A which is disposed in sliding contact with a semi-spherical recess 2 A formed in a piston 2. The convex semi-spherical surface 1 A is defined by a convex surface of a revolving body which is formed when an arc of a circle having a radius of R 2 and having a center C offset from the axis L of the semispherical shoe in an direction orthogonal thereto is rotated about the axis L as a center of rotation. A lead-in 1 G which is arcuate in section is formed toward the top of the convex semi-spherical surface 1 A and maintains a clearance 7 with respect to the semi-spherical recess 2 A. A lubricant oil which is stored in a space 4 is smoothly supplied onto a sliding surface 1 F through the clearance 7. The invention provides a semi-spherical shoe 1 having a good sliding response and an increased length of useful life.

What is claimed is:  
     
         1 . A semi-spherical shoe including a convex semi-spherical surface fitted into a semi-spherical recess formed in a first movable member for sliding movement thereto, and an end face disposed in sliding contact with a flat surface on a second movable member; 
 characterized in that the convex semi-spherical surface which is in sliding contact with the semi-spherical recess in the first movable member is defined by a convex surface of a revolving body which is formed when an arc of an circle offset by a given distance from axis in a direction orthogonal thereto is rotated about the axis as a center of rotation.    
     
     
         2 . A semi-spherical shoe according to  claim 1  in which when the radius of the semi-spherical recess in the first movable member is denoted by R 1  and the radius of the arc by R 2 , a difference R 1 -R 2  is chosen to be greater than 150 μm.  
     
     
         3 . A semi-spherical shoe according to  claim 1  or  2  in which the distance by which the center of the arc is offset from the axis in the orthogonal direction is chosen in a range from 20 to 500 μm.