Abstract: A magnetic recording and reproducing system including a reel base for supplying or taking up a tapelike magnetic recording medium, and a tension band for braking the reel base, which is wound around the reel base through a predetermined angle. First and second retainers are provided for holding opposite ends of the tension band, respectively. The first and second retainers are pivotally attached to a pivotal tension arm. The tension arm has a tension post so that the magnetic recording medium is brought into sliding contact with the tension post. An urging member is provided for adjusting the tension of the magnetic recording medium to a desired value. The system also includes a control member which has a contact portion capable of being brought into contact with a guide portion of the second retainer.

Abstract: A rotating shaft section of a rotation cam gear supported on the chassis side and transmitting the driving force of a driving motor can be inserted into and removed from a rotating shaft section of a mode detection switch for detecting a mode from the rotating position of the rotating cam gear. A protruding pointed portion and a groove that are fitted to each other to transmit the rotational force of the rotating cam gear are formed in these rotating shaft sections. Output terminals of the mode detection switch are coupled and attached to the circuit section of a circuit substrate, and the rotating shaft section of the mode detection switch is inserted into the rotating shaft section of the rotating cam gear supported on the chassis side to engage the protruding portion with the groove. This constitution enables easy and smooth insertion and fitting of the rotating shaft sections, thereby improving working efficiency.