Anyone know what the proper name for this is, and how to adjust it?

It's on my Peruzzo ditch and bank mower. It's on the cylinder that swings the mower head out to the side. It's purpose is to limit damage if the mower head hits an obstacle when being swung out. But it seems to be set to release at too low a pressure for my hilly property. When I try to swing the head out while the tractor is pointed down a steep hill (21 degrees - 40%) and the head has to be pushed back up the hill, or on a side hill where the head has to swing up hill, the valve releases and the head doesn't move. This is true even if the mower is off the ground.
So I think the solution is to set the valve for a higher relief pressure. But how?
Taking off the cap exposes a threaded rod, with a hex socket in the end. So I suppose one takes off the cap, loosens the jam nut, and turns the threaded rod. But which direction sets it for a higher relied pressure? How many turns to have an effect?
Any info welcome.

It's on my Peruzzo ditch and bank mower. It's on the cylinder that swings the mower head out to the side. It's purpose is to limit damage if the mower head hits an obstacle when being swung out. But it seems to be set to release at too low a pressure for my hilly property. When I try to swing the head out while the tractor is pointed down a steep hill (21 degrees - 40%) and the head has to be pushed back up the hill, or on a side hill where the head has to swing up hill, the valve releases and the head doesn't move. This is true even if the mower is off the ground.
So I think the solution is to set the valve for a higher relief pressure. But how?
Taking off the cap exposes a threaded rod, with a hex socket in the end. So I suppose one takes off the cap, loosens the jam nut, and turns the threaded rod. But which direction sets it for a higher relied pressure? How many turns to have an effect?
Any info welcome.