Is this hydraulic system open or closed? What is the best way to add a 3rd spool to add a grapple rake. This machine only has a two spool valve. I have found a Prince 3 spool valve for loaders that looks like it will work but how do I determine if its an open or closed system?
Generally you have to add a third valve to the two valve block. As I recall they stack on. You will also also have to have a pilot valve. The loader hydraulics on all the Komatsu loaders I've worked on were open center but the pilot system is closed center. You should really get a service manual before you go changing things. I've not seen a Prince valve with enough flow to be able to use it for a wheel loader. Not saying they don't make one, just that I haven't seen one. Maybe the manufacturer of the rake will have a kit or some suggestions.