What device is used to regulate pressure from an engine-driven hydraulic pump?

The device that is specifically tasked with regulating pressure from an engine-driven hydraulic pump is a pressure regulator. A pressure regulator maintains the output pressure of the hydraulic fluid at a predetermined level, ensuring that the system operates within safe and efficient limits. This component adjusts the flow of fluid from the pump based on the demand of the hydraulic system, preventing pressure spikes that could potentially damage components.

While other options have their roles in a hydraulic system, they do not function as pressure regulators. Flow control valves manage the flow rate rather than pressure, system bypass valves act to divert excess flow or protect the system from overpressure conditions but do not regulate ongoing pressure, and check valves prevent backflow in the system but do not control pressure levels. Thus, a pressure regulator stands out as the appropriate choice for stabilizing hydraulic pressure generated by the engine-driven pump.