S V Hi-Tech Bearing (India) Private Limited

Solenoid valves are control units which, when electrically energized or de-energized, either shut off or allow fluid flow. The actuator takes the form of an electromagnet. When energized, a magnetic field builds up which pulls a plunger or pivoted armature against the action of a spring.
basic purpose of a solenoid coil is to convert electrical energy into mechanical energy to supply linear motion. The structure of a solenoid coil includes a coil of wire that is wrapped around a piston made of a ferromagnetic metal.
Solenoid works on the principle of electromagnetism. When the electric current passes through the coil, the magnetic field is generated. When a metal core is placed inside the coil, the magnetic lines of flux are concentrated on the core. This increases the induction of the coil as compared to the air core.
An electric current through the coil creates a magnetic field. The magnetic field exerts an upwards force on the plunger opening the orifice. This is the basic principle that is used to open and close solenoid valves.

Hydraulic Actuator