| 摘要 |
PROBLEM TO BE SOLVED: To efficiently drive a plurality of cooling fans with minimum energy required to cool hot water to the specified temperature with a simple device and with a simple control. SOLUTION: A plurality of cooling fans 4A, 4B, 4C and 4D are driven respectively by hydraulic motors 12A, 12B, 12C, 12D, at least one hydraulic motor 12A is driven by a variable displacement pump 14, and other hydraulic motors 12B, 12C, 12D are driven by fixed displacement pumps 31, 32, 33. When the displacement of the variable displacement pump 14 is increased, one fixed displacement pump which is stopped by approximately maximum displacement of the pump 14 is started, the displacement of the pump 14 is reduced to control the temperature of cold water. When the displacement of the variable displacement pump 14 is reduced, one fixed displacement pump which is started by approximately minimum displacement of the pump 14 is stopped, and the displacement of the pump 14 is increased to control the temperature of cold water.
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