Solenoids or Solenoid Valves are small electric devices used to control the flow of air in an air suspension system. We stock 12v dc solenoids which are operated by conventional car and van electrics. Most solenoids have two electrical wires – power and earth. they are normally closed and will not allow air to flow. When power is applied to the circuit the solenoid opens and air flows. When power is withdrawn it closes again. In this way solenoids can be used to control the lifting and lowering of vehicles. 2 solenoids per vehicle corner are required – i.e. 4 per axle, and 8 in total. They can be wired to use 6 for a full vehicle but this is unusual.