A two-bladed folding propeller with synchronous folding and unfolding of the baldes is only suited for use at high speeds of rotation. In order to be able to utilize the advantages of the folding propeller with a three-bladed propeller, the synchronization of the baldes according to the invention is designed with a toothed bar (8) provided with teeth either in the form of an annular cogging, or in the form of even coggings on the side surfaces of a prism-shaped toothed bar. This permits the baldes (18) to be fitted on the hub (4) and their teeth (16) to mesh with the teeth of the toothed bar (8) in such a manner that a three-bladed propeller can operate as a folding propeller.
