Oh my! Backdragging can be MURDER on hoses, especially if you hit a rock, a tree stump, or anything else. If you backdrag with your bucket only down at a 45 degree angle, you will probably be okay. That's because it will lift up the front of your tractor and only a small pressure spike will be felt. If you go beyond 45 degrees and approach 70 to 90 degrees down, the pressure spike is more pronounced and may be huge. Why doesn't the relief valve stop any high pressure spike? Because the relief valve is only in the circuit when the joystick is not centered. I put that in bold because it is so important to understand. When you backdrag, you rotate the bucket down and then hold it in position by centering the joystick or only moving it slightly. The centered joystick valve isolates the loader hydraulic from the rest of the hydraulic circuit including the relief valve.
In the hydraulic circuit, the loader physically cannot drop because of the relief valve. Have you ever heard of someone carrying a very heavy load and have it drop because the relief valve popped open? I don't think so. The strength of the hoses, metal tubes, joystick valves, and hydraulic cylinders all have to be much higher than the pressure relief valve pressure. I like to use 4000 psi working pressure hoses. Their bursting pressure is way above 4000 psi. If you T'd in a pressure gage and left it there while you were operating, you'd be surprised, I'm sure.
At some point, I have busted all four of my OEM curl/dump cylinder hoses on my tractor. I have four 4000 psi hoses and a spare I keep for emergencies. If you think about it, you can have your loader cutting edge down and be dozing with it and hit an obstruction too. That will surely also cause a spike and may pop a hose. Once you understand how the loader hydraulics and joystick work, it makes you a bit more careful. At least that was true in my case. I'm always careful to backdrag at high angles only if I'm in very loose materials where I am sure there is no obstruction.:thumbsup:
