Simple one this!
When I was on night trunk, I was sent solo from Derbyshire to Essex to pick up a trailer in a lay-by that had been repaired in situ.
I got there, coupled up to the trailer and started to wind the legs up and SNAP, the bolt connecting the winding handle to the crossbar was no more 
It was 1am so not best pleased and couldn’t find anything to replace it so it was head scratching time. I then had a thought, how about my metal tin opener
so I gave it a try and hey presto - RESULT! Lesson learned and hence forth, a spare nut and bolt always carried in my spares bag.