Abstract: A ring binder mechanism includes a housing that supports two hinge plates for loose pivoting motion, moving the ring members apart or together. The mechanism also includes an actuating lever pivotally mounted on the housing. The lever moves a travel bar and its locking elements for controllably pivoting the hinge plates and the ring members mounted thereon between closed and open positions. In particular, the locking elements cam the hinge plates to softly close the ring members. When the ring members are apart, the locking elements register with openings in at least one of the hinge plates. When the ring members are together, the locking elements are substantially out of registration with the openings, blocking the hinge plates from pivoting to separate the ring members. The travel bar is formed with reinforcing structure to resist deforming the travel bar upon repeated operation.