I am a beginner in hydraulics and excavators..I have recently studied the operational circuit of HITACHI EX-60 mini-excavator..I have few doubts which i could not understand..
1. why use two pumps to power the hydraulic system instead of single pump with same P-Q characteristics?
2. the control valve is kayaba 80. why the the two spools are used each for BOOM, ARM actuators rather one spool for each of them?