Hydraulic transmission device

A hydraulic transmission device comprising:

• a housing having a closed end portion and an open end portion;
• a drive shaft supported within said housing by being inserted through a through hole formed in a substantially central location of said closed end portion of said housing;
• a retainer having a spherical outer surface and formed integrally with said drive shaft;
• a cylinder block provided within said housing and formed integrally with said drive shaft, said cylinder block having a recess at a substantially central location on the side thereof that is closer to said open end portion of said housing;
• a cover member which closes said open end of said housing and has a protruding portion which is in engagement with said recess of said cylinder block through a bearing;
• a port plate which is provided between said cover member and said cylinder block and is slidably engageable with the end surface of said cylinder block that is on the side of said open end of said housing;
• a plurality of pistons provided in said cylinder block and received in a plurality of cylinders so as to reciprocate therein, said cylinders communicating with fluid suction and discharge hole portions formed in said port plate and said cover member;
• a swash plate operationally engaged with said pistons;
• shoes secured to said swash plate for receiving front portions of said pistons respectively;
• and
• return plates disposed between the respective shoes and said retainer in a springy manner.