Patent ID: 8616296

Claim:
A mobile soil aeration device comprising: a machine frame, a drive, at least one guide arm moved up and down by said drive and arranged in a pivotable manner at said machine frame, the guide arm comprising at least one piercing tool coupled with the guide arm in an articulated manner, said piercing tool being adapted to be pushed into the soil and to be pulled out from the soil, a tool holder for the piercing tool, which is supported for movement about a first pivot axis in the guide arm adapted to be moved up and down by the drive, so as to allow for a pivoting of the piercing tool with respect to the guide arm during engagement in the soil, wherein, prior to piercing, the piercing tool is in a start position under a predetermined piercing angle, and wherein a restoring element is integrated in a second guide arm coupled in an articulated manner with the machine frame and the tool holder, wherein the second guide arm is variable in length, such that the restoring element allows the pivoting of the tool holder about the first pivot axis, wherein, after the piercing tool has been pulled from the soil, the restoring element engaging the tool holder pivots the piercing tool back to the start position, wherein the restoring element engages the tool holder at a distance from a plane extending through the first pivot axis and in parallel to the tool holder and the piercing tool and offset in the direction of a restoring force of the restoring element acting on the tool holder, whereby a lever arm of the restoring force active about the first pivot axis is enlarged at least at a maximum deflection of the tool holder relative to the start position, wherein the restoring moment acting on the tool holder after have been pulled from the soil, when the tool holder has the maximum deflection, is higher than the restoring moment acting on the tool holder prior to piercing, when the tool holder is in the start position.