| 摘要 |
PURPOSE:To prevent a tractor from being abruptly started, and improve the feeling of the driving and the safety, by providing a stepless speed change gear and a step speed change gear having a neutral step, and making the stepless speed change gear forcibly at a minimum speed when the neutral step is assumed. CONSTITUTION:When shift lever is placed in position, a control valve 13 is set correspondingly to feed the hydraulic pressure 12 to clutches CL1-CLR to change the speed. By a toggle switch (not shown) of the shift lever 11, pulley halves 21a, 21b of a sub-transmission are moved to change the speed of an input shaft 29 of a power shift PS in a stepless manner. When the shift lever 11 is placed in a neutral position, a control valve 13 is placed in an N-position, and at the same time a limit switch is actuated to magnetize a solenoid 24d of an electromagnetic valve 24 so that a piston rod 23 is moved forward and backward, and the pulley halves 21a, 21b are moved away to set the input shaft 29 of the power shift PS at the minimum speed. Thus, the tractor can be prevented from being abruptly started and the feeling of the driving and the safety can be improved. |
