| 摘要 |
PURPOSE:To raise lubrication oil temperature at an early time by releasing temporarily brake effect that is by means of an HST at the time of coldness in the winter season, increasing the operation frequency of a mechanical type brake. CONSTITUTION:The closed circuit connection of a variable displacement type hydraulic pump 2 driven by means of a motor 1 and a hydraulic motor 5 that drives drive wheels 11, is made by means of a pair of main pipe passages 3, 4. A bypass pipe passage 17 is provided between main pipe passages 3,4 and made openable/closable by means of an opening/closing valve 18. An oil temperature sensing switch 22 is provided at a circuit that extends to the solenoid coil 18a of the onening/closing valve 18 from a power source 20 through a main switch 21, and when the detection temperature of an oil temperature sensor 25 to detect the lubrication oil temperature of a motive power transmission mechanism 10 has arrived at more than a fixed value, the solenoid coil 18a is magnetized. An acceleration switch 23 that falls into a non- electrification state in a state in which an acceleration pedal is not stepped on, its provided, and when the acceleration pedal is stepped on in connection with a relay 24, the magnetization of the solenoid coil 18a is stopped. |
