This is a two-level ambulance cot which was manufactured by Ferno-Washington and is believed to be a Model 22. It required two users in order to properly raise and lower the patient. One user would need to stand at the head of the stretcher, then use their foot to push in the middle locking bar. Then, while the other user was at the foot, both would carefully lower the stretcher to the ground, attach the retainer clips to the bottom rail on both sides and then lift the cot into the ambulance. To raise the stretcher, the reverse process was used. 

2-Level Stretcher