Hydraulic drive urinal flushing system

A hydraulic drive urinal flushing system comprising:

• a weight sensor;
• a hydraulic cylinder having a piston reciprocating therein, and a piston rod upwardly extended from said piston and connected to a bottom side of said weight sensor, said hydraulic cylinder holding a hydraulic fluid;
• a return pipe connected in parallel to said hydraulic cylinder on the outside, said return pipe having a top end and a bottom end respectively connected to said hydraulic cylinder at different elevations;
• spring means mounted around said piston rod and connected between said weight sensor and said hydraulic cylinder, said spring means imparting an upward pressure to said weight sensor;
• a hydraulic fluid delivery pipe having a first and second end,said first end connected to said hydraulic cylinder at one side opposite to said return pipe at an elevation between the top end and bottom end of said return pipe;
• and
• a normally biased closed valve connected to the second end of said hydraulic fluid delivery pipe, said valve having a valve body responsive to said hydraulic fluid for controlling a supply of flushing water to a urinal;
• wherein when a user steps on said weight sensor, said weight sensor is lowered to compress said spring means, and said piston is lowered with said weight sensor and said piston rod to force the hydraulic fluid out of said hydraulic cylinder through said hydraulic fluid delivery pipe into said valve, thereby causing said valve body of said valve to be opened, enabling water to pass to the urinal;
• the hydraulic fluid is returned from said valve through said hydraulic fluid delivery pipe to said hydraulic cylinder when said piston is lowered in said hydraulic cylinder below the elevation of said hydraulic fluid delivery pipe;
• said weight sensor is pushed upwards by said spring means to lift said piston in said hydraulic cylinder when the user steps off of said weight sensor, thereby causing the hydraulic fluid to be forced out of said hydraulic cylinder through said hydraulic fluid delivery pipe into said valve, and therefore said valve body of said valve is opened again to let water pass to the urinal.