| 摘要 |
In a hydraulic power lift for tractors, with a three-point linkage (11) for coupling working appliances (20), with a working cylinder (17) for raising and lowering the three-point linkage (11) and with control hydraulics (21) acting on the working cylinder (17) and having traction-resistance sensors (26) controlling a regulating valve (22) via a regulating linkage (25), there is provided, to achieve a high uniformity of the furrow depth when a mounted plough (20) is coupled, a ground tracer (39) which acts via a lever mechanism (42) on an actual-value lever (24) of the regulating linkage (25), the said actual-value lever (24) controlling the regulating valve (22). Depending on the change in position of the ground tracer (39), a raising or lowering pulse is transmitted to the working cylinder (17) in the regulating valve (22). The raising or lowering pulse is limited by an actual-value lever return device (43) which is integrated in the lever mechanism (42) and which, via a cam disc (44) rotating together with the three-point linkage (11), resets the actual-value lever (24) to its neutral position, in which the regulating valve (22) locks the working cylinder (17) hydraulically. <IMAGE>
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