I'm pretty good at locking myself out so when I made up my pneumatic door I added a key operated switch on the side of the cowl. You can just make out the pair of key switches--one for the door the other for the compressor. The upper switch operates an air solenoid that causes the door to open or close dependent on the position of the key. The lower switch is for the compressor. I've managed to run the air up without thinking about the door and would have been badly locked out without the switch. Once the door is closed, its mechanism (pirated from a transit bus) locks the door closed from the outside even after the air pressure has drained off. Jack
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