Sun Hydraulics Relief Valve

relief valve
Used at the discharge of a positive displacement pump. An adjustable, spring-loaded valve opens when a preset pressure is reached. Used to prevent excessive pressure buildup that could damage the pump or motor.
safety valve: a valve in a container in which pressure can build up (as a steam boiler); it opens automatically when the pressure reaches a dangerous level
The relief valve (RV) is a type of valve used to control or limit the pressure in a system or vessel which can build up by a process upset, instrument or equipment failure, or fire.

hydraulics
(hydraulic) moved or operated or effected by liquid (water or oil); "hydraulic erosion"; "hydraulic brakes"
Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties.
Hydraulic systems, mechanisms, or forces
fluid mechanics: study of the mechanics of fluids
The branch of science and technology concerned with the conveyance of liquids through pipes and channels, esp. as a source of mechanical force or control

sun
Sit or lie in the sun
Expose (something) to the sun, esp. to warm or dry it
sunlight: the rays of the sun; "the shingles were weathered by the sun and wind"
the star that is the source of light and heat for the planets in the solar system; "the sun contains 99.85% of the mass in the solar system"; "the Earth revolves around the Sun"
expose one's body to the sun