Model: T10 Parallel Guide of Beranger
This mechanism maintains two horizontal platforms in parallel for small motions of the device. Such mechanisms are used for weighing mechanisms. This linkage is also an example of an over-constrained assembly of links and joints that, were it not for the symmetry, would be a rigid truss. The mobility of this linkage of eight limbs and eleven cylindrical joints is equal to minus one, according to the classic mobility criterion (see tutorial). However, the symmetry of the linkage allows small motion. Attempts at larger motions prove fruitless as the linkage will lock up.

Francis Moon 2004-07-00

Reference :

  • Grübler : Getriebelehre (Getriebelehre: Ein Theorie des Zwanglaufes und ebenen Mechanismen. Verlag von Julius Springer, Berli, 1917)