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A pull solenoid is an electromagnetic actuation device that supplies a linear working motion towards the solenoid coil. This is in contrast to push solenoids that develop their working motion away from the solenoid coil. This working movement comes courtesy of an electromagnetic field that develops around a wire coil when it is energized with an electric current. The magnetic attraction of the field pulls a metal plunger rapidly towards the coil. The movement of the plunger is then harnessed to provide actuation for a secondary mechanism, such as a valve, switch, or machine component.
Solenoids are the simplest of all electric actuators, with far smaller physical dimensions, less moving parts, and lower overall installation and running costs than electromechanical types. Their operating principles are simple, and revolve around the powerful attraction that a magnetic field holds for any ferrous metal object. The average solenoid consists of a hollow wire coil and a spring-loaded, ferrous metal plunger placed adjacent to, or just inside, the mouth of the coil. When an electric current is applied to the coil, the tightly-coiled windings create a strong electromagnetic field around it. This field attracts the plunger, which moves smartly into the center of the coil, providing linear actuation movement in the process.
There are two basic linear motion solenoid types available: the push and the pull solenoid. The push solenoid is so configured that, although the basic functioning is identical to the pull variety, the working motion is directed away from the coil with a pushing movement. The pull solenoid is generally a little simpler in construction and generates its motion towards the coil. As mentioned, the core functioning of the two types is identical with only the plunger design differing. The choice of which type is used in any given application is generally dictated by space and the specific actuation requirements of the secondary mechanism.
The pull solenoid is a common component on a wide variety of systems that require remote switching or actuation. These include many automotive applications such as valves and vents. The industrial sector is also a significant user of solenoid products, with a wealth of fluid and gas flow, electrical control, and machine actuation processes being driven by solenoids. Other solenoid users include the chemical, pharmaceutical, and medical industries. The pull solenoid is also encountered in a large number of domestic applications, such as cleaning equipment, water valves, and air conditioning system components.