• A Jackhammer uses a pneumatic solenoid.jack hammer, man working image by Greg Pickens from Fotolia.com
  
  Many times there is a need to move something. This basic need has given rise to numerous mechanisms to create motion, from simple levers to the use of solenoid components. Where once a person may have applied the force required to move the object, now the solenoid can provide the force. Solenoids are self-contained units that can provide precision motion in many situations.
  
  

Parts & Function

• The internal parts and working of a solenoid are all basically the same. There is a mechanism that applies a force to a piston. The piston is typically metal. This mechanism will vary depending on the force that it creates. There is a shaft enclosure that houses this mechanism and the piston when it is withdrawn.
  
  Of the different forces that are used to move the piston, the most common are pneumatic (air) and electromagnetic. Pneumatic force is often used to push the piston out. These units are sometimes used to raise lids. In other units, an electromagnetic force may be used to pull the piston in. These units can be used to close lids. An electromagnet can be used to push as well, and pneumatic pressure can be used to pull. In many solenoids, there is a mechanism designed to return the piston to its rest position as well.
  
  

External and Internal Switching

• With many solenoid units that are used as components, there are two basic switching mechanisms. There is an internal switching in some and an external switching in others. The internal switching is a switch located in the solenoid. This switch shuts off the force that causes motion in the solenoid piston. This switch is typically triggered when the piston is withdrawn completely or when the piston is extended completely. It is useful in ensuring that the solenoid is not burned out by running after the action has completed.
  
  An external switch is one that allows solely for the switching on and off of the solenoid by an external source. This switching allows an operator to switch the solenoid on and off as needed. This greater amount of control can be useful in a number of applications, however improper use can result in damage to the unit and other components. A timer unit can also be considered an external switch as well as a number of other control mechanisms that are external of the solenoid.
  
  It is possible to combine an internal and external switch. This can create a level of control and safety that is practical and beneficial for most applications.
  
  

Placement

• Depending on the construction of the solenoid, it may be essential that you place the unit with the piston pointing down. Because the motion of the piston relies on as little friction as possible, there is generally space for minute debris and dust to slip between the piston and the casing. This can result in damage and reduced efficiency. It is also essential that the unit be positioned to allow straight-line motion of the piston and straight-line pressure against the piston.
  
  The construction and the mechanism used to create the force that causes motion can make a solenoid unit sensitive to certain conditions. These conditions commonly include moisture and temperature. Each unit will typically have documentation that details the conditions that it can function under.