Radial piston type hydraulic pump-motor

A radial piston type hyraulic pump-motor comprising:

• a cylinder block formed with a plurality of radial cylinders circumferentially equally spaced and each opened at its radially outer end;
• a plurality of piston assemblies each radially slidably accommodated in each of said radial cylinders of said cylinder block to provide a cylinder chamber defined by said radial cylinder and said piston assembly;
• a plurality of inlet-outlet passages each including a horizontal bore disposed between said adjacent two piston assemblies and radially outwardly of a radially inner end of said radial cylinder, said horizontal bore horizontally extending throughout and opened at the side faces of said cylinder block, and a cylinder bore having one end opened at said cylinder chamber defined when said piston assembly is moved to the radially inward stroke end and the other end communicated with the longitudinally intermediate portion of said horizontal bore;
• a housing accommodating therein said cylinder block and said piston assemblies and having a radially inner face held in contact with the radially outer ends of said piston assemblies;
• at least an introducing passage partially formed in said housing and including a main introducing passage having one end exteriorly opened and a plurality of branch introducing passages having one ends opened in communication with the other end of said main introducing passage and the other ends opened circumferentially equally spaced and communicatable with the other ends of said inlet-outlet passages;
• at least a discharge passage partially formed in said housing and including a main discharge passage having one end exteriorly opened and a plurality of branch discharge passages having one ends opened in communication with the other end of said main discharge passage and the other ends opened circumferentially equally spaced and communicatable with the other ends of said inlet-outlet passages in alternative relation with the other ends of said branch introducing passages;
• and
• a shaft connected rotatably with said housing and coupled with said cylinder block.