| 摘要 |
PROBLEM TO BE SOLVED: To provide an HST capable of increasing output at any time according to the work content by deciding capacity of the HST according to normally frequently used output demands. SOLUTION: In a hydrostatic continuously variable transmission (HST) 12 having a variable hydraulic pump 31 and a hydraulic motor 32 driven by this hydraulic pump 31, port pressure applied to a tilt angle switching port 41 of the hydraulic motor 32 can be changed to two stages by switching of a directional control valve 42, and this directional control valve 42 is switched by a solenoid valve 45. A stepping quantity of an HST pedal 21 is detected by a potentiometer 39 to judge whether or not an arm exists in a raising position by an arm angle sensor 28. In an arm lowering position, a controller 40 regards a work load as large to set the solenoid valve 45 in an opening position (a truncated chevron shape mark) to switch the directional control valve 42 to a position (a square shape mark). Thus, a tilt angle of the hydraulic motor 32 becomes large, and output torque of the HST 12 becomes high torque. |
