Human Immunodeficiency Virus, commonly known as HIV, is a virus that affects the immune system by destroying white blood cells known as CD4 cells. These cells are responsible for fighting disease.
Servovalve, Hydraulic-Description. A hydraulic servovalve is a servo (see Servo, Hydraulic â Description) with a device (either flapper nozzle or jet pipe) used to position the servo. The term electrohydraulic servovalve is often used because servovalves are controlled through an electrical signal.
Piston valve (steam engine) Piston valves are one form of valve used to control the flow of steam within a steam engine or locomotive. They control the admission of steam into the cylinders and its subsequent exhausting, enabling a locomotive to move under its own power.