To provide a coolant supplementing device automatically supplementing coolant while restraining a temperature change of the coolant in a tank and simple in setting it.
This coolant supplementing device has: a sub tank 2 to reserve the coolant 7; a supply passage 3 to communicate the sub tank 2 to a main tank 1 of a working facility; two check valves 4, 5 to prevent back-flow of the coolant 7 to the side of the sub tank 2 from the side of the main tank 1 by serial arrangement to the supply passage 3; and an air cylinder 6 to suck and discharge air by relative movement of a door 16 and a door frame 15. The air cylinder 6 is communicated to a liquid reservoir chamber 9 formed between the check valves 4, 5 of the supply passage 3, the coolant is sucked in the liquid reservoir chamber 9 from the sub tank 2 by suction of the air of the air cylinder 6, and the coolant in the liquid reservoir chamber 9 is discharged to the main tank 1 by discharge of the air of the air cylinder 6.
Torii Kazuhisa
Takayoshi Tagawa
Higashio Masahiro