Abstract: A wetting device for flat mops includes a mechanical elevator that contains a contact structure, brackets, and plastic slide bars. The brackets lift the transfer plate away from the lower end of the wetting device if the contact structure is pressed towards the lower end. Each bracket is connected to at least one plastic side bar. The plastic slide bars move apart from each other when the transfer plate lifts away from the lower end. The transfer plate lies upon the plastic slide bars during movement of the plastic slide bars apart from each other. Each plastic slide bar has a length that is at least five times larger than its maximum width and is detachable from its corresponding bracket. The contact structure is a flat metal framework of connected struts. Also disclosed is a cleaning trolley with the wetting device.