A walk-in chamber has a door opening closable by a door, which, when in the closed position can be either in a locked position or an unlocked position, dependent on the locking device, which includes a sliding bolt engageable with a locking bolt. Scissors linkage at the rod ends can move the rods in unison between the open and close configurations. Other embodiments include annular coil springs which compensate for component wear, and contraction and expansion due to changes in temperature.