Critically Damped systems and Overdamped Systems

[jrm2002]

A critically damped system is one in which the system does not
oscillate and returns to its equilibrium position without oscillating.

Even, in an overdamped system the system does not oscillate and returns
to its equilibrium position without oscillating but at a slower rate
compared to a critically damped system.


My questions are:


1) An automatic door close is an example of an overdamped system.Right?
I want to know how is this overdamping property achieved in an
automatic door closer practically?


2)Can anyone give an example of critically damped system and again tell
me how are the characteristics of being critically damped achieved
practically?
Please help!!

[Cyrus]

1.) No, it is critically damped. Critically damped systems return to the equilibrium position in the shortest amount of time. It is achieved by viscous damping inside the piston cylinder actuator of the door.

2.) A gun is made critically damped so that it returns to the neutral position in the shortest amount of time between firing.

[jrm2002]

Thanks for the response:
1)You said,
"--- A gun is made critically damped so that it returns to the neutral position in the shortest amount of time between firing."

You mean after the bullet leaves the gun,

it ("it" refers to the gun) returns to the neutral position in a short time??

2) You said that the critical damping in a door closer is achieved by viscous damping inside the piston cylinder actuator of the door.

I wanna know how viscous damping is achieved during manufacturing of the door closer?What components inside the door closer contribute to critical damping?

Thanks again

[Cyrus]

http://en.wikipedia.org/wiki/Door_closer