In article ,
Ned Simmons wrote:

On Tue, 24 Nov 2009 18:18:55 -0600, Tim Wescott
wrote:

A really heavy duty screen door damper that worked in reverse (i.e. damps
on the way out instead of the way in) would be absolutely perfect.

Most hydraulic shocks damp when the piston is pushed in, but though
I've never used them, I think I have run across reverse acting units.

I just finished messing with the struts on my car. They mostly damped
with the piston going out: though there was some damping force in both
directions, it was much stronger when pulling them out.

This is as it should be: when going over a bump, the shock should be able
to compress easily, so that the wheel goes up and the tire doesn't suffer
too much; damping can be done on the way down, when the worst that can
happen from too much damping is for the tire to lift off the road. So I
expect that most automotive shocks are that way. A visit to a friendly
local auto parts store would likely turn up a unit suitable for Tim's
application. (If there is such a thing as a friendly local auto parts
store near him -- one that'd let him browse their selection, rather than
just demanding the make and model of the car it is to fit. That might
take some finding.)


--
Norman Yarvin http://yarchive.net