Fluid clutch

A fluid clutch for coupling a first shaft and a second shaft which are arranged on the same axis, said fluid clutch comprising:

• a casing drive-coupled to said first shaft and having a plurality of pump chambers;
• a gear pump including a first pump gear disposed in said casing, drive-coupled to said second shaft, and having a gear formed on the outer periphery thereof, and a plurality of second pump gears disposed in said plurality of pump chambers and in mesh with said first pump gear, wherein:
• an intake passage is formed in said casing and in said second shaft and communicates with an intake port of said gear pump;
• an exhaust passage is formed in said casing and in said second shaft and communicates with an exhaust port of said gear pump;
• a supplementary passage communicates said intake passage and said exhaust passage;
• and
• said fluid clutch further comprises a control valve disposed in a valve hole formed in said second shaft said valve hole communicating with said intake passage and with said exhaust passage to control a communication area between said intake passage and said exhaust passage, and check valves disposed between said supplementary passage and said intake passage and between said supplementary passage and said exhaust passage, to permit the flow of fluid from said supplementary passage to said intake passage and to said exhaust passage.