Load sensing steering system.
This system is fixed by pump, priority valve, load sensing PSU, steering relief valve and system relief valve.

Pump---The system can adopt a fixed displacement pump, pressure compensated pump or pressure and flow compensated pump. When a fixed displacement pump is used, the auxiliary circuit must be open center. When a  pressure and flow compensated pump is used, the auxiliary circuit must be load sensing or closed center.

Priority Valve ----The priority valve must be matched with the max.
flow of the pump and priority flow requirement of  the PSU. The Min.
control pressure must assure adequate steering flow rate.

Static signal PSU must be matched with Static signal priority valve.

LS Pilot Line ----The Ls pilot line is used to pass the pressure signal from PSU to priority valve.
The length of the LS pilot line is no more than two meters. 

Advantage

Reliable Steering----Provides reliable steering because the steering circuit always has flow priority.

Save Energy----In the neural position of PSU, only a little oil flows back to the tank. So the system saves energy.