The present invention makes it possible to avoid having to dismantle greenhouses in order to use special machines, and proposes a mechanism with built-in automation, mainly for working agricultural surfaces. It is characterised by a system for automatically lifting up the tool holder towing beam (5), the beam being equipped with a translating system and its tool-holder carriage (9) driven by an offset drive system. The automatic translation system allows the various tasks to be programmed either in terms of space (surfaces to be worked) or in terms of time (sequencing of the work) by the use of removable teeth located on the running path or any sensors and use of a programmable automaton. The mechanism allows application to just one greenhouse or to several greenhouses in parallel. <IMAGE>
