Good day all y,All. I have a 1989 JD 790D excavator. I am in the midst of adding an auxiliary circuit for a mulching head. I had picked up a Brown Brontosaurus 4.0STM hammer flail mulcher for proposed land clearing. It takes about 50 gpm to run, 5000 max psi. I have an existing aux spool on the 790D's main valve body. I have supply and return hoses from the valve body to the 3 additional steel lines up the boom, and also a return case drain back to reservoir. I have pilot lines from the valves to the cab. My questions are: Do I need to add pressure relief/anti-cavitation valves in lieu of the plugs currently in place on the main valve body? Similar to the adjacent dig circuit... A recommendation for an in cab valve for the pilot control lines. I'd like something with a lever and graduated as a throttle. Not anything just on/off. A recommendation for an adjustable volume control between 0-50 gpm for 3/4" lines. And best location for it. And lastly, any thoughts, suggestions, admonitions on the project. What could I possibly be overlooking. What could I be doing that may be simpler, or safer. Appreciate any help.
Welcome to HEF Trog . The machine will have very limited to no swing capability if using the auxiliary spool to supply the mulcher. Need to install a dual priority valve or (2) single priority valves fed from both hydraulic pumps to supply the mulcher.
Thanks for the reply DD. The total pumps' output is supposedly rated at about 125 gpm. If using only 50 gpm for the mulcher, wouldn't the balance be enough for lift/swing or minimal travel? That's 75 gpm. Or am I misunderstanding the workings?
New flow spec of each pump is 62.5 GPM x 2= 125 . The 4 spool side of the main control valve is supplied by one pump and the 5 spool side which contains the swing and the auxiliary spool is supplied by the second pump. There would be at best only 12.5 gpm to operate the swing.
Ahh, ok. I get it now, thanks. An obtuse moment. Would you know of any JD or Hitachi models that may have the priority valves to be scavenged off? I doubt my budget would allow a new priority kit. I'll have to make do with second hand and modify. Also, any suggestions on cab controls ? Or a volume control? I'm assuming the question on pressure relief valves would be a moot point.
I don’t know of any Deere/Hitachi excavators that have factory installed priority valves. The cab control for the mulcher operation will be an on/off switch to power up the priority valve solenoid(s).
Would the optimum design have a 5 port priority valve? Two 1" lines inlet from dual pumps, two 1" lines outlet to machine main valve body and the mulcher priority port. Or should the pump supply lines be combined before the priority valve and split after? Using a 3 port priority. Seems there would be a volume loss or pressure increase this way. I have only been able to find one manufacturer of a 5 port thus far. BoschRexroth, out of Italy. Please share if you know of any others. I see Gorilla offers some plumbing kits. Are there any companies affiliated with the forum that might offer appropriate priority valves? Thanks much
A 5 port dual priority would be ideal but (2) 3 port priority will certainly work. If using (2) 3 port valves, the individual pump outlet would supply an individual priority valve, the controlled flow port (to the mulcher) from each valve would be teed together.
WELCOME MATE
Lynch Fluid Controls has dual pump priority “hammer” valves. https://www.lynch.ca/Products/hammer-valves.php .
Thank you DD I reached out to them to see what they had that might accommodate my needs. We'll see what they come back with. Appreciate the contact. I'm in communication with Gorilla hammers as well but no decent resolution there as yet.