I would call this type of device a bellcrank. It is often used to change the the direction and motion ratio of cable and rod assemblies. Very common in model airplanes and probably old real ones that used cables and rods for the controls.
I did some interesting engineering work with cables at one time. Within
this device is a cable/rack motion multiplier (shown in a schematic, it
rather difficult to figure out when folded up in the mechanism) and a
parallel motion cable system.
http://www.freepatentsonline.com/
Joe Bender-Zanoni Little Falls, NJ
Harvey M Sachs wrote:
> I first saw a "demultiplicator" decades ago, just after most of the
> transition between "plunger" and parallelogram derailleurs. The
> plungers needed to take up a LOT of cable, so their shifters, often
> braze-on, had a large "barrel" diameter. Parallelograms take much
> less cable movement. So, the folk wisdom was that the demultiplicator
> (what an ugly word!) served to reduce cable throw, allowing you to
> keep your old DT shifter lever when you converted to the new derailleur.
>
> There's a little irony here: I'm using one on my Hetchins, which has
> early Shimano bar-cons, to space out the lever throws a bit - the
> application that Bob Hanson suggested.
>
> harvey sachs
> mcLean VA USA
>
> +++++++++++++++++++++++++++++++++++
> Bob Hanson wrote:
> Can someone please explain this piece to me?
>
> This was the relay attachment hinged to the rear derailleur cable guide
> which would be clamped above your bottom bracket (on the down tube).
>
> Was this intended to simply reduce the distance of travel on your rear
> barcon shift lever? And, was this useful?... Necessary?... Just a weird
> French 'truc'?
>
> Nobody else used anything like this, only Simplex, so I assume there was
> something uniquely quirky about their "cross-commandes" [barcon levers]
> alone.
>
> Curious if these shifters actually functioned well,... especially with
> this additional bit of French technology designed into that system.
> I've never known anyone who has actually used a set.
>
> [Whaddya think, Jerry?]
>
>
> Bob Hanson, Albuquerque, New Mexico, USA