The L-1011 pax doors had a long curved rack on each side with gear teeth down its length. The gear teeth on the racks engaged with gears on a shaft above the door. At one end of the shaft was an electric actuator with a brake assembly incorporated. It normally operated the door. At the other end of the shaft was a counter-balance unit. Inside were gears and a stack of Bellville springs. As the door was closed, a small jackscrew insside compressed the springs. This provided the power to open the door in an emergency.
The racks on each side of the door had a series of small arms attached.. The other end of each arm was attached to the door. So except when down, the door was suspended from the arms. When, on closing, the door reached the bottom it engaged with a ramp that started to force it outward. The door could not go down any more but the racks, driven by the actuator could. The arms were down from the weight of the door but as the racks proceeded down the arms pushed outward forcing the door into its seat.
The counterweight spring on the shaft above was now fully compressed, It stored enough energy to rapidly raise the weight of the door AND the slide-raft pack attached to the door and drag the apron of the slide raft pulling out of the pack to deploy it. I can assure you there was not enough power there, nor the mechanical advantage of those arms on the rack to overcome any cabin pressure. I saw several emergency evac TESTS fail because the apron of the slide raft was improperly packed and the door did not have enough power to drag the chute out. It stalled at about 2 feet ope.
Sorry so lengthy. It actually was a very good door and, except for brakes that would slip after long use, casused little trouble. And yes, its design originated in the L-188 Electra.