A torsional vibration insulator for a drive train of a vehicle, in which a primary element and a secondary element can rotate relative to one another. At least two spring elements extend in an arc in a circumferential direction of the rotational axis and are each supported on a radial outer face by a radial support device. The length of the two spring elements, viewed in the circumferential direction, can be modified by rotating the primary element with respect to the secondary element. The radial support devices of the spring elements have multiple support elements which engage with the radial outer face of the spring elements and which are rotatably mounted in the circumferential direction in such a way that the support elements can be carried along with the spring elements in the circumferential direction when the length of the spring elements is modified, thereby eliminating frictional forces inhibiting rotational motion between the primary element and the secondary element.