This European Standard specifies safety requirements for the design and construction of unloaders mounted in stationary round silos for the removal of the silage and similar materials. It applies to electrically powered, slowly rotating unloaders which operate on top surface of the stored silage surface. It describes methods for the elimination or reduction of hazards for which specific requirements on unloaders, as defined in 3 and shown in Annex B, are necessary. In addition, it specifies the type of information to be provided by the manufacturer on safe working practices. The document only deals with the hazards generated by the silo unloader and not with those of the silo system itself (e.g. hazards arising from generated gases). This document is not applicable to noise and fire hazards and hazards related to the foreseeable misuse.The document does not deal with technical requirements for installation or removal of the unloader from one silo to another. The list of significant hazards dealt with in this document is given in annex A. Annex A also indicates the hazards which have not been dealt with. The environmental aspects have not been considered in this document. This document applies primarily to machines which are manufactured after the date of issue of this document.NOTE Directive 94/9/EC concerning equipment and protective systems intended for use in potentially explosive atmospheres can be applicable to the type of machine or equipment covered by this European Standard. The present document is not intended to provide means of complying with the essential health and safety requirements of Directive 94/9/EC.