Patent ID: 8602120

Claim:
A mobile soil working device, comprising a machine frame, a drive for at least one piercing tool which can be lifted and lowered, the piercing tool being operative to pierce the soil and to be withdrawn again, a guiding element, moveably guided on the machine frame, for at least one piercing tool, wherein before the piercing the piercing tool is located in a starting position at a predetermined piercing angle, a tool holder for the piercing tool, which holder is pivotable around a first pivot axis in the guiding element that can be lifted and lowered by said drive in order to allow for the piercing tool to be pivoted relative to the guiding element during engagement with the soil, where, at least after withdrawal of the piercing tool from the soil, a restoring moment acting around the first pivot axis is exerted onto the tool holder, so that the piercing tool pivots back again into the starting position, wherein that the overall center of gravity of the tool holder and said at least one piercing tool is arranged in relation to the first pivot axis in such a manner that the moment of inertia of the tool holder and the piercing tool that counteracts said restoring moment, is overcompensated to the effect that the moment of inertia acting around the first pivot axis forms at least part of the restoring moment.