Abstract: An embodiment rail device includes an upper rail, a first bearing support on the upper rail, a lower rail, a bearing connection end on the lower rail and inserted into the first bearing support, a vertically elongated bearing contact adjustment hole on the lower rail, an upper bearing rotatably connected to the bearing connection end and in close contact with a floor of the first bearing support, a lower plate including a fastening groove that receives a lower end of the lower rail, a bearing shaft mounting hole on a wall surface portion of the fastening groove and matched with the bearing contact adjustment hole, a second bearing support outside the fastening groove and having an opened upper portion, a lower bearing rotatably disposed within the second bearing support, and a bearing shaft fastened to the bearing shaft mounting hole and the bearing contact adjustment hole by a screw.

Abstract: An embodiment is a seat height gear system including a monopost apparatus configured to be mounted under a seat, the monopost apparatus comprising a lower post and an upper post, and a direct drive motor apparatus within the monopost apparatus, the direct drive motor apparatus including a motor and a gear unit, the gear unit including a pinion and a rack bar, the rack bar being configured to be engaged with the pinion, the motor being fixed to the lower post of the monopost apparatus, the pinion being coupled to the motor, the rack bar being fixed to an upper post of the monopost apparatus, the motor being configured to rotate the pinion, and the rack bar being configured to convert the rotation of the pinion into the linear motion.

Abstract: An embodiment rail device includes an upper rail, a first bearing support on the upper rail, a lower rail, a bearing connection end on the lower rail and inserted into the first bearing support, a vertically elongated bearing contact adjustment hole on the lower rail, an upper bearing rotatably connected to the bearing connection end and in close contact with a floor of the first bearing support, a lower plate including a fastening groove that receives a lower end of the lower rail, a bearing shaft mounting hole on a wall surface portion of the fastening groove and matched with the bearing contact adjustment hole, a second bearing support outside the fastening groove and having an opened upper portion, a lower bearing rotatably disposed within the second bearing support, and a bearing shaft fastened to the bearing shaft mounting hole and the bearing contact adjustment hole by a screw.