1. A force-balance pneumatic regulator comprising a supporting plate, a pair of boxes fixed to said supporting plate to provide air chambers, bellows moving equipment contained in each of said boxes, a balance, a supporting plate, a resilient cross fulcrum for said balance comprising upper and lower platforms pivoted, respectively, to said balance and said overhead plate and solidly connected to said supporting plate, and pairs of double L-shaped flexible blades welded at the ends of a diameter of said platforms to join them together, and means to vary the gain of said regulator.

2. A force-balance pneumatic regulator comprising a supporting plate, a pair of boxes fixed to said supporting plate to provide air chambers, bellows moving equipment contained in each of said boxes, a balance, a supporting plate, a resilient cross fulcrum for said balance comprising upper and lower platforms pivoted, respectively, to said balance and said overhead plate and solidly connected to said supporting plate, and means to vary the gain of said regulator comprising a rack keyed to the pivot for said upper platform, a toothed idler gear mounted on the overhead plate and meshing with said rack, and a tie rod hinged to said balance and to the supporting plate so that its axis lies on the plane containing the oscillation axis of the balance.