Abstract: A film drive for a motion-picture camera or projector has a film drive wheel which is rotatable about a first axis and has a plurality of angularly equi-spaced and radially extending teeth. A function cam rotatable about a second axis spaced from and perpendicular to the film axis has a generally helical peripheral formation which engages with the teeth of the wheel. This helical formation includes an intermittent-drive section having a holding portion constituting almost a complete turn of the formation of zero degree pitch and a switching portion at each end of the holding portion of predetermined pitch greater than zero degrees, and a constant-drive section of constant pitch greater than zero degrees and axially offset from the intermittent-drive section.