Variable displacement hydraulic piston pump with torque limiter

A variable displacement hydraulic piston pump comprising:

• a housing means having an open-ended housing and an end covering closing one end of the housing;
• a drive shaft rotatably supported in said housing means;
• an inclinable swash plate pivoted in said housing means to take a position between a predetermined small inclination-angle position thereof substantially parallel with a plane vertical to an axis of said drive shaft and a predetermined large inclination-angle position thereof inclining far from the plane;
• a cylinder block mounted on said drive shaft to be rotated about an axis thereof together with said drive shaft;
• the rotatable cylinder block being provided with a plurality of axial cylinder bores arranged parallel with the axis of said drive shaft;
• a plurality of axial pistons reciprocatorily fitted in the plurality of cylinder bores, respectively, and engaged with said inclinable swash plate via shoes;
• a valve plate arranged in close contact with an end of said rotatable cylinder block and having suction and discharge ports capable of being in cyclic communication with each of the plurality of cylinder bores;
• the suction and discharge ports being in constant communication with fluid suction and discharge bores formed in said end covering of said housing means, respectively;
• a resilient means arranged in said housing means for constantly urging said swash plate toward the small inclination-angle position thereof;
• a hydraulic control cylinder means arranged in said housing means for providing said swash plate with a controlled force to move said swash plate to a desired position between the predetermined small and large angle positions thereof against said resilient means;
• a hydraulic opening and closing control valve means arranged in a hydraulic circuit of said hydraulic control cylinder means for controlling the introduction of pressurized oil into said hydraulic control cylinder means;
• an input shaft rotatably supported in said housing means for transmitting a rotary drive power from an external drive source to said drive shaft;
• and
• a torque limiter means arranged between said input shaft and said drive shaft for disconnecting the transmission of the rotary drive power from said input shaft to said drive shaft in response to an overload encountered by said drive shaft.