I have a shaft inside a bushing, the shaft has a gear on one end that is supposed to provide resistance to other gears it is driven with.

I'm having a hard time finding the correct term for the sort of grease or fluid, or in more lay-man's terms a "goo", that will provide increased friction between the shaft and the bushing, rather than reducing friction, as it is with regular oil or grease.

Essentially a tar-like substance, that isn't as messy as actual tar. Perhaps also similar to tree-sap, except more manageable in terms of putting it into a mechanical device. Also tree-sap gets hard over time, I'd like to keep its mechanical properties, like viscosity, etc.

In case you're wondering, this is going to be part of a soft-open gearing, such that a small door doesn't fling open when the lock is released, instead it provides some resistance.

  • 2
    $\begingroup$ It sounds like you're looking for increased damping, not friction per se. There's a lot of shock-absorber and dashpot designs out there; it may not be worthwhile to reinvent the wheel. $\endgroup$
    – TimWescott
    Mar 28, 2019 at 2:59
  • $\begingroup$ I totally agree! There is absolutely no reason to reinvent the wheel. I would stick to a solution that already exists. $\endgroup$
    – Daniel H.
    Mar 28, 2019 at 15:29

2 Answers 2


They are called haptic greases. Used on knobs and levers to provide stiction but very smooth movement when actuated.

Here's an explanation from Nye Technologies - https://www.nyelubricants.com/motion-control

  • $\begingroup$ "haptic damping grease" did the trick. Finally, I'm not poking in the dark anymore, thanks! $\endgroup$
    – polemon
    Apr 23, 2021 at 15:00

That made for some interesting links... You may be looking for shear thickening lubricant. According to the Wiki page, some of these products can also be called non-Newtonian fluids, but I would not suggest cornstarch and water for your application.

Additional research resulted in a question posted "elsewhere" that suggests the product you seek is rare, uncommon and difficult to find. One application listed is as projectile defense in body armor!

I have seen slow opening devices which use a cylinder linkage in which the cylinder allows "normal" fluid to travel through a circuit with a restricting opening. Think about a syringe in that you have a large diameter plunger and a small diameter needle. Plenty of force does not result in rapid travel.

One can create a closed system similar to a syringe using air as the working fluid, if one can drill a small enough hole in the restrictor plate.

Additionally, I have seen speed limiters that use a high gear ratio assembly to spin a simple squirrel-cage impeller fan. Similarly, there is arresting gear for exiting a building that also uses a spinning fan of paddle wheel design.

Because you used "small" in your question, I suggest paddle wheel or squirrel cage fans may not work well in tiny scale, but a cylinder and orifice can be reduced and still be effective. You can get away with a clean wall cylinder and a piston with such tight tolerances that the entire perimeter is the orifice. If properly machined, no seals (o-rings) would be needed, only a light lubricant and possibly periodic lubing.

  • $\begingroup$ I've seen similar things in cassette decks that had one of these soft-open things. it was essentially a little stick that slid in and out of a little receptacle filled with a resistive fluid like that. The stuff should be stable, i.e. not slowly leak out, etc. The only thing I could think of right now, is using blobs of paper glue, they keep their gooey and sticky texture at least for a long while. $\endgroup$
    – polemon
    Mar 28, 2019 at 1:03
  • $\begingroup$ Glycerin is a liquid that does not harden in the same manner as glue and is of reasonably high viscosity. It's slippery but not really a lubricant for mechanical purposes. It will make your skin silky and soft, however. $\endgroup$
    – fred_dot_u
    Mar 28, 2019 at 13:17
  • $\begingroup$ Well, I'm not making a lotion, it's supposed to provide friction without stiction. $\endgroup$
    – polemon
    Mar 28, 2019 at 19:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.