US Patent 7484814 Hydraulic system with engine anti-stall control

A hydraulic system has first and second functions in which separate control valves govern the flow of fluid between actuators and both a supply conduit and a return conduit. The second function is connected to a load sense passage. When pressure in the load sense passage exceeds a given level an anti-stall valve opens a restricted path between the supply and return conduits. Fluid flow through that restricted path reduces a likelihood that a prime mover driving the pump of the hydraulic system will stall. When only the first function is active the anti-stall valve is closed and does not affect the supply of fluid to that function.