Brake Device, Drive Unit, and Industrial Device

A brake device including a first device having a shaft; a brake element having a first frictional brake surface and an engageable structure; a second device rotatable relative to the first device about a rotation axis, the second device including a second member having an opening, a second frictional brake surface, and a forcing member pre-tensioned to force the second frictional brake surface against the first frictional brake surface; and an actuator connected to the first device, the actuator including an engaging structure movable between a disengaged position, and an engaged position to brake relative rotation between the first device and the second device about the rotation axis; wherein the shaft is concentric with the rotation axis and passes through the opening.