Posted by Andy Baker at 1/29/2001 1:12 AM EST
Engineer on team #45, TechnoKats, from Kokomo High School and Delphi Automotive Systems.
In Reply to: Re: double solenoids...
Posted by Josh on 1/29/2001 12:47 AM EST:
Double solenoids don't really lock the cylinders any better than the single solenoids do. They both will hold the cylinders in position. The only time that a cylinder will lose it's position is when pressurized air is dumped from the system.
A doulbe solenoid shifts the valve from one side or the other by means of a quick pulse of the solenoid. Once the valve is shifted by solenoid A, it travels over to the B side. The valve will stay there until it is shifted by solenoid B, back to the other side.
A double solenoid should be used on a cylinder that is held in either the extended or retracted position. This type of valve will keep a cylinder in position even after electricity is shut off to the valve. (maybe this is what Josh meant by "locking"
.
A single solenoid valve will hold a cylinder in the actuated position as long as the solenoid is getting a signal to actuate. But, when the solenoid is not moved, the valve will keep the cylinder in it's unactuated state, if you plumb the tubing right. If you set up the tubing so that the cylinder is vented during the unactuated state, then it will move freely... but it won't be forced into the unactuated position once the solenoid is de-activated.
For more technical help, get your local SMC, Festo, Clippard, Bimba, or Parker salesperson to help you out... they may even want to give you free tools, along with some technical advice.
Andy B.