| 摘要 |
PROBLEM TO BE SOLVED: To reduce an untilled part due to a shallower tilling depth of a tilling device than a target tilling depth in a structure for controlling the lifting and lowering of the tilling device of an agricultural tractor. SOLUTION: This structure for controlling the lifting and lowering of the tilling device 4 of the agricultural tractor is capable of operating a lifting and lowering mechanism 5 and driving the lifting and lowering of the tilling device 4 so that the tilling depth D of the tilling device 4 is maintained at a target tilling depth, setting the operating speed of the lifting and lowering mechanism 5 to the high speed side with increasing difference between the tilling depth D of the tilling device 4 and the target tilling depth and setting the operating speed of the lifting and lowering mechanism 5 to the low speed side with decreasing difference between the tilling depth D of the tilling device 4 and the target tilling depth. When the tilling device 4 is made to be lowered and driven from a state of a shallower tilling depth D of the tilling device 4 than the target tilling depth, the operating speed of the lifting and lowering mechanism 5 set by a speed setting means is changed to a higher speed side.
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