Definition
A hydraulic system component that maintains pressure within a preset operating range by directing pump output to the system when pressure is low and unloading the pump (routing its output back to the reservoir at low pressure) once the system reaches its upper pressure limit. It allows a constant-displacement pump to operate efficiently without continuously building heat or overpressuring the system.
Plain English
A device that keeps hydraulic pressure between a set high and low value. When pressure gets high enough, it lets the pump rest by sending its fluid back to the tank instead of into the system. When pressure drops, it puts the pump back to work.
Context Anchor
Seen in aircraft hydraulic system maintenance, especially when checking pressure control for equipment such as landing gear, flaps, brakes, or flight controls.
Derivation
Regulator comes from a Latin root meaning “to guide or control.” That helps here because the part’s job is to control pressure in the system, not to create the pressure.
Why Pilots Care
Maintains reliable pressure for brakes, flaps, and landing gear operation, preventing system failures.
Analogy
Think of it like a thermostat for hydraulic pressure. When the system has "enough," the regulator switches the pump to idle. When the system needs more, it switches the pump back on.
Intuition Check
Do not assume the regulator is the pump. The pump supplies hydraulic flow and pressure; the system-pressure regulator controls that pressure so it stays within limits.
Example Sentence 1
When the system-pressure regulator failed in the kicked-in position, the pump kept loading the system and the relief valve had to open to prevent damage.
Example Sentence 2
During preflight, low system pressure indicated a possible issue with the system-pressure regulator.