Treasure adventure game miner boss problem

I got stuck on "miner boss" (that giant two-legged miner drill that the pirates pilot and that throws dynamites on me) and i can not find a way to hurt him.

All I found out by trial and error is that when i hit it into cockpit that animation shows as if energy shield was present, but no animation suggesting that it would be hurt by it. when i try to throw bomb on it, it just falls trough.