Align the hole of the Rail (2) with the Main Frame
(1). Then lock with the Φ30×Φ10×δ2.5 Big Washer
(33) and M10×20 Knob (34) with clockwise direction.
CAUTION:
Move with caution when you vertically fold the Rail (2), as your head may touch the Rear Support
Stabilizer (4).