The invention relates to a roller (1), preferably comprising two wheels (2) and a locking device, an activating part (10) acting on the locking device for releasing or locking, and the activating part (10) being movable by a drive, a movement of a transmission part (7) that is generated by the drive being transmitted via spring force to the activating part (10) for moving same, and a spring (8) being supported on the transmission part. In order to provide a roller that allows an advantageous constructional design, it is proposed that a support region is formed for the spring (8) and/or the spring (9) and/or the compression spring (44) on the activating part (10), through which region the transmission part (7) can pass.