Artillery when was introduced and number of it

[Frank]

The romans usually didn't carry Scorpions or Catapulta with them, they just lopped off the useful part (the torsion spring housing) with an axe and re-built the rest later. They also took the metal parts.

That makes a lot of sense for the bigger equipment, but does it make sense for the smaller stuff like a carroballista to disassemble it always?

http://en.wikipedia.org/wiki/Carroballista

Or look at this. Even if I doubt, that there is a proper evidence for this construction

http://wattsunique.com/blog/wp-content/u...llista.jpg