PURPOSE: To prevent the occurrence of the seizure or the like of a hydraulic motor or the like by accumulating charging pressure oil in an accumulator during a travel for a work, and feeding the pressure oil to a close circuit, when a clutch mechanism is turned on, regarding a hydraulic continuously variable transmission made of a hydraulic pump and a hydraulic motor.

CONSTITUTION: In this continuously variable transmission for a traveling work machine, power transmission to the input shaft 5 of a hydraulic pump 6 is turned on and off via a clutch mechanism. Also, travel wheels are jointed via a transmission gear to the output shaft 5a of a hydraulic motor 6a connected like a close circuit with the pump 6, a high pressure hydraulic circuit 60 and a low pressure hydraulic circuit 61. In this case, an accumulator 9 with a selector valve 9a is provided at the intermediate section of the charging pressure oil circuit 65 of a charging pump 6c driven with the input shaft 5 for feeding charging pressure oil to a close circuit 67, and the valve 9a is connected to the operation member 7 of the clutch mechanism for an interlocked operation. Also, the valve 9a is selected via the operation of the member 7 for turning on power, thereby enabling the charging pressure oil of the accumulator 9 to be fed to the close circuit 67.