Comments by "Keit Hammleter" (@keithammleter3824) on "Hydraulic Cylinder Rod is Stuck and Bend Due to the Hitting of Heavy Stone | Check How it's repaired" video.

Before straightening it in a press, they heated it to destroy its strength. From that point on, it is ruined and the straightening quite pointless. It could be re-hardened, but I can't imagine that these little shops have the means to do that. The cylinder is of course a write-off. The way it was bent suggests that it was bent (probably nowhere near as much) before and was repaired the same way - and didn't last.
9
@richardmaurer9002 : It's the extreme degree of bending. If they hit an immovable rock with the bucket while using the machine with a good cylinder and rod in place, not a lot will happen. I've done it with a bulldozer and it just stopped the hydraulics dead with no damage done. Hydraulics don't move things fast enough to build up much kinetic energy. With an old machine with worn hydraulics you just MIGHT get seal failure / fluid blow-out. To get a massive bend like this, would need something heavy hitting the actual rod side on, as might happen if you are demolishing abuilding with a back-hoe - as (say) the operator crashed the bucket into a brick wall to collapse the wall and a heavy roof beam fell down over the rod - possible but not particularly likely. In use, all the load on hydraulic rods & cylinders is longitudinal - there is no side force to induce bending. So if it bent this bad when they hit a rock, a) it must have been already at least slightly bent, and b) it was weakened for some reason, as would be the case if they heated it as they did in this video.
4
@roundedges2 : Probably. I have no idea how, but I've seen enough of these Pakistani small shop videos to realise they'll tackle just about anything - probably involving much use of a hammer, oxy-acet cutting and welding, and much dodgy work on a lathe..
1