Not a lot of experience with hydraulic systems but. Seems like basic physics. I have a huber warco grader that I belive I found d the pressure relief on. It has a inoperative solenoid on it. It is connected to 3 switches that I assume go to ground if the system worked. What the solenoid does when energized is mearly a guess. The switches are connected to the right side blade down. The left side has no switch. 2 switches are connected to the blade angle, I assume one each way it moves. Again my assumption is it increases pressure/volume when engaged. I could easily be wrong. Question, can I dump this for a manual adjustable relief. If so what pressures should I look for. I don't have an issue with compromise as it's not a production blade. Do I need to know the pump output I would guess. I haven't. Even able to find info on the pump yet. Any information or opinions are helpful.
Removed the pump just to check it, turns out it was rebuilt and in near perfect internal shape. Also it had another tag on it. Both tags were riveted on. Also repaired the solenoid. Slowly making progress, the 3 switches may be a challenge as they are not straight forward in their wiring.
I am a bit confused. I must be missing something as when the gauge is hooked up I have minimal pressure showing and then 500 psi when a cylinder is engaged. The pump deadhead at 1100 psi. It doesn't really matter I guess as I can still get a pressure reading. When the solenoid is physically engaged all pressure is dumped so I'm a bit confused by that as well. Again not sure any of this matters. I think I'm going to get an adjustable valve when I can figure out the volume then adjust it to 800 to 1000 psi as 500 psi nearly raises the front end with the blade at idle.
Haven't even seen a Huber is some years but the way what you are describing sounds like a quick drop valve to me. Hopefully someone more experienced than me will pop in shortly to tell me I'm wrong.
Never heard of a quick drop valve. Will have to look into it. A quick approximate calculation leads to 11 gpm when using lift speed etc. As large as the pump and gears are I have to believe it's output should be more. There is a place where the pump line splits at the valve bank. 1 line goes through the valves to a singe port valve with no control. I suspect it may be the steering line. Then it goes back to the tank. The other line goes to this relief/drop? Valve then returns to the tank
I think I should have said a blade float valve. Is this one of those machines that look like a long tractor with the blade underneath? I believe Huber also made some conventional road graders as well.
Conventional, at least in the looks department . Not so sure in the engineering part anymore. I had a bit to see what a quick drop valve is and I don't believe it is that based on the application. I was totally wrong in my first post. The 3 switches are actually on the right blade up and the cicle swing both directions not blade angle. This is assuming that the switches have something to do with the solenoid. I assumed as much as the wire while not connected did run there. I appreciate your responses as it makes me learn and think. And wonder why I bought an orphan.
Im curious as to why my pressure gauge reads 0 until I pull a lever or steering wheel. then goes to 5-600 psi. I believe its plumbed correctly. Its on the pressure side of this valve. Maybe this valve isnt even a pressure relief but I cant find anything else in the system and it appears to be in a proper placement as well.
The pump are gear pumps and the hydraulic system is open center which means the oil goes through the valves and then back to the tank usually passing through a hydraulic filter on the way. You don't get any pressure until there is a resistance to flow by routing the flow to something like a hydraulic cylinder or a motor. The pressure will rise until something moves. Relief valves are put into the system and in each circuit to let flow go back to the tank when something won't move. Internal wear in gear pumps can be seen in the cases and the end plates. Worn pumps can be witnessed by slow movements of the implements or lack of power and plenty of heat in the system. Can you take some photos of the machine and the hydraulic valves and post them up here?
Heres an image I didnt post from the pump. Ill get more pics this evening. Thanks for the explanation. Makes sense. The pump will deadhead at 1100 psi.
Actually i suspect my conclusion about the pump deadheading at 1100 psi is probably incorrect, more likely its the relief opening when I bottom out the cylinder. The light bulbs are slowly starting to go on. The pump was tight and had little if any end play of the only gear I could measure it on.