Pump failure alarm system for hydraulic working machine

A pump failure alarm system installed in a hydraulic working machine comprising a plurality of hydraulic pumps driven by at least one prime mover, a plurality of delivery lines introducing respective flows of a hydraulic fluid delivered from said plurality of hydraulic pumps and joining with one another into one common line on the downstream side, a plurality of check valves provided respectively in said plurality of delivery lines upstream of a point where said plurality of delivery lines join with one another, at least one hydraulic actuator driven by the hydraulic fluid introduced through said common line, and a hydraulic reservoir, said pump failure alarm system comprising:

• a plurality of pressure detecting means for detecting respective delivery pressures of said plurality of hydraulic pumps,
• a plurality of bypass lines having one ends connected respectively to said plurality of delivery lines at points upstream of said check valves and the other ends connected to said hydraulic reservoir,
• a plurality of opening/closing means disposed respectively in said plurality of bypass lines for opening and closing the associated bypass lines,
• alarm means for giving an alarm to an operator in correspondence to each of the plurality of hydraulic pumps, and
• control means for controlling the opening/closing operations of said opening/closing means and the alarming operation of said alarm means in accordance with the results detected by said pressure detecting means.