When does the compound leverage patent expire?

[ReamerPunch]

Remember how Gerber's sliding plier patent expired? And we got the Leatherman OHT?
When does SOG's compound leverage patent expire? So others can take a swing at it?

[dks]

Was it an international patent? If that is possible.

I think they expire after 25 years in the US, from what I remember from various posts (could be wrong), though some can be renewed.

Is it a SOG exclusive or was it used by other companies too? (maybe exclusive for multitools only)

[ReamerPunch]

There are tools that have compound leverage, so maybe it is not patented? Or it was and has expired already?
Or is its use in multi-tools patented by SOG? Probably not.

[Noa Isumi]

I know SOG did patent it because they would often tout that uniqueness in their advertising.
The only 'non-SOG' multitool I know of to use the feature is the Stanley licenced version of the PPP which has "compound leverage pattented" stamped on the frame. Given that aside from the markings it is identical to the SOG I believe these were SOG made, but never looked into it.
Given other tools use compound leverage the patent is most likely multitool specific.

[Vidar]

There is no such thing as a world patent, so like anyone else they could never had that in the first place. If you cover the most important markets a lot is done though.

As for compound leverage mechanisms there are many different ones. It is highly unlikely they covered them all in the first place - for one there are normal compound pliers, scissors and various compound special tools available. Not to mention compound mechanisms used in machinery and mechanical devices. Their patent most likely covers a subset of compound leverage mechanisms well suited for folding or compact tools.

One reason other companies haven't been very interested in making one handed compound tools might be that it doesn't make much of a difference for many cut geometries? The SOG design have two main issues in that regard: 1. There is a limit to how wide a hand can grip (which is why most compound bolt cutters are for two hands and spread very wide), and 2. The plier fulcrum design is the same as for normal pliers.

So as a thought experiment imagine opening the plier to max hand grip width and put a round wire into the plier cutting jaws: Due to the 2:1 (or so) compound mechanism, and the hand grip width limit, the SOG plier will only open half as wide as the ordinary plier in the same hand. Thus the round wire will be about twice as long from the plier fulcrum compared to a wider opened normal plier. The grip force needed to cut depends on the distance from the fulcrum as well as the compound - so what is gained one place is largely lost at the other. (Though with more parallel plier cutters which is a benefit - as  long as the round wire fits).

As for just gripping compound is great as long as it fits the narrower plier mouth.