I was playing with a wheat light a few days ago. I can't understand what holds the bulb in beside pressure from the lens.

Most light bulbs of that nature insert and rotate a few degrees to lock in. Looking at the socket it doesn't allow the bulb to rotate, Is there some others mechanism that I'm missing?

"I can't understand what holds the bulb in beside pressure from the lens."

nope, nothing you got it. its designed that way so if youre in an explosive atmosphere and you brake the glass and bulb and expose the filament it will not explode the air/methane mixture. the bulb will just simply fall out. they were originally designed with a spring on the bulb so it will be ejected out the front instead of relying on it to just fall out but through out the years most have lost the spring in routine bulb replacements. i know some of ours have them, but my spare and a few others we have the spring is missing. there is nothing wrong with your lamp its just working the way it was designed

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