Adams HatchLatch solenoid

This is one of the stupidest inventions in modern vertical transportation - the Adams HatchLatch. The HatchLatch is a door restrictor system that controls the operation of this giant-ass steel bolt and solenoid. When power is removed from the solenoid, the elevator cab door is locked very securely and it is necessary to gain access to the top of the cab to successfully rescue anyone inside. The system has no failsafes and no provision for remote manual release, and is quite capable of locking an otherwise correctly operating elevator's door either closed... or even open, likely burning out the door operator. It is controlled by a few optical sensors (which get dusty and fail in short order) that detect when the cab is in the door zone, and when the door operator is TRYING to open or close the door... if these conditions are all met, it pops the pin up, then drops it a couple seconds later. You can hear the pin fall a couple seconds after the door fully opens.

The best maintenance procedure for the Adams HatchLatch is to bend up the upper plate above the steel pin's mushroomed top until you can just move the pin past it, then hang the pin's top on the edge of that plate, permanently jamming it in the up position. This is fully reversible for when the inspector arrives. :P

See how the Adams HatchLatch caused many people to lose their lives in elevators that fell along with the New York City World Trade Center towers here: http://www.elevatorbobs-elevator-pics.com/wtc4.html