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I bought a pair of soft close, undermount type drawer slides. Being a card carrying PF member, the first thing I did was examine the soft close feature to see how it works. Apart from general curiosity, I have seen video advertisements where they demonstrate how you can close the drawer with a smart little kick, which is then supposed to be absorbed by the soft close feature.
The fixed slide carries a dashpot (with presumably a spring hidden inside). The dashpot is coupled to the moving slide via a hook type catch. When you pull the moving slide out, then at some point the catch unhooks from the moving slide and hooks onto the fixed slide, so that the dashpot no longer follows the moving part. From this point on you have nearly zero damping. The spring is now latched in the fully-extended state and is waiting for the drawer to be closed.
If you push the moving slide back inwards (or let it move back under its own weight), then again at some point it unhooks the dashpot from the fixed slide and latches itself onto the dashpot's shaft. This action now allows the internal spring to kick in and slowly draw the slide into the fully closed position.
A potential flaw is revealed if you try to see how the impact of a fully loaded, kicked-in drawer might be absorbed. Ideally, the damping should kick in gradually, or else a buffer spring should decelerate the drawer at a reasonable rate before the final closing velocity is reached. In the system that I bought, if you allow the moving slide to fall nearly vertically into place, you can feel a pretty hard shock as the latch flips and the damping kicks in abruptly. The brunt of this shock is taken by the latch itself, which is made from a couple of small plastic parts.
So in this particular design, those small plastic parts probably won't last if they have to transmit that large decelerating force from the dashpot to the drawer, slowing it down significantly within hardly a millimeter of travel.
So if you have looked at this kind of mechanism, maybe yours was better designed? If you have also overthunk this issue, what are your thoughts?
The fixed slide carries a dashpot (with presumably a spring hidden inside). The dashpot is coupled to the moving slide via a hook type catch. When you pull the moving slide out, then at some point the catch unhooks from the moving slide and hooks onto the fixed slide, so that the dashpot no longer follows the moving part. From this point on you have nearly zero damping. The spring is now latched in the fully-extended state and is waiting for the drawer to be closed.
If you push the moving slide back inwards (or let it move back under its own weight), then again at some point it unhooks the dashpot from the fixed slide and latches itself onto the dashpot's shaft. This action now allows the internal spring to kick in and slowly draw the slide into the fully closed position.
A potential flaw is revealed if you try to see how the impact of a fully loaded, kicked-in drawer might be absorbed. Ideally, the damping should kick in gradually, or else a buffer spring should decelerate the drawer at a reasonable rate before the final closing velocity is reached. In the system that I bought, if you allow the moving slide to fall nearly vertically into place, you can feel a pretty hard shock as the latch flips and the damping kicks in abruptly. The brunt of this shock is taken by the latch itself, which is made from a couple of small plastic parts.
So in this particular design, those small plastic parts probably won't last if they have to transmit that large decelerating force from the dashpot to the drawer, slowing it down significantly within hardly a millimeter of travel.
So if you have looked at this kind of mechanism, maybe yours was better designed? If you have also overthunk this issue, what are your thoughts?
