r/Hydraulics

Got a bobcat 430hag mini excavator. Whilst redoing all the seals I have found this solid metal ring between the gland and the piston on my stick cylinder. Is it just a spacer? There were no o rings between it and the piston or gland when ibtook it off but now putting it back together I have one left over out of the kits wich is loose on the rod. Ther is a worn groove on the bottom of the gland where it looks like Ther may have been a prong at one stage. Cannot find any mention or diagram that includes this metal ring let along another o rings

... on the (presumably 2-stage) pump on my wood splitter? And why might fluid be leaking out from underneath it when in use?