Coupled Brownian motors on a tilted washboard

We consider globally coupled particles, each of them governed by a determin istic relaxation dynamics in a critically tilted washboard potential, but w ithout a preferential spatial direction for the coupled system as a whole. For weak-to-moderate coupling we observe a spontaneous breaking of the syst em intrinsic symmetry which entails a spontaneous collective transport via a ratchet effect, possibly with a superimposed oscillatory long time behavi or. For strong coupling, spontaneous symmetry breaking and spontaneous dire cted current are ruled out, whereas a negative mobility in response to an e xternally applied force is recovered.