Abstract: A diaphragm pump having at least two working chambers communicating with inlet and outlet chambers via non-return valves, includes a reciprocal wobble plate affixed to a diaphragm in the working chambers. The wobble plate has a central guide shaft with a carrier at its free end, the carrier having resilient material, such as a rubber coating or rubber blocks, associated with it. A groove in a rotor connected to a drive shaft receives the carrier. The slope of the guide shaft with respect to the drive shaft is adjustable, and the resilient material holds the carrier in a preset eccentric position with respect to the drive shaft so that under overload conditions the carrier will press against the resilient material and reduce the eccentricity of the carrier with respect to the drive shaft. Once the overload conditions no longer exist, the guide shaft returns to its normal position and normal pumping continues.