<p>The invention relates to a locking device to radially lock a rotatable cylindrical element, where the locking device (1) comprises a roller element (2) and at least a first inclined surface (3). The locking device is arranged to be positioned in relation to a cylindrical surface (13) around the cylindrical element (12) in such a way that the distance between a starting point (10) of the first inclined surface (3) and the cylindrical surface (13) is larger than the diameter of the roller element (2) and that the distance between an end point (11) of the first inclined surface (3) and the cylindrical surface (13) is smaller than the diameter of the roller element (2). The locking device further comprises means (6) to selectively enable the roller element (2) to be distanced from the cylindrical surface (13). The advantage of the invention is that a locking device can be obtained in an easy and cost-effective way.</p>
