Weighing device with strain gages

Claim 1

A weighing device comprising a base plate (1) and a platform (2) for carrying the load to be weighed, said platform being substantially parallel to said base plate, at least one metal bar (3) being placed between said base plate and said platform, the opposite ends (3a, 3b) of said bar being rigidly fixed to said base plate (1) and to said platform (2) in order to permit flexural deformation of said bar under the action of the load applied on the platform, said bar being adapted to carry flexure-sensitive strain gages (4, 5, 6, 7) connected electrically in a Wheatstone bridge circuit (8) and torsion-sensitive strain gages (9, 10) connected to said bridge circuit in order to cancel the torsional stresses detected by the flexure-sensitive strain gages, the bar (3) being provided on one and the same flat face (3c) with two pairs (4, 6; 5, 7) of flexure-sensitive strain gages substantially aligned on the longitudinal axis (X--X') of the bar, wherein the gages of each pair (4, 6; 5, 7) are connected in opposition in the Wheatstone bridge and wherein two torsion-sensitive strain gages (9, 10) are coupled in series and connected respectively to the supply terminals (A, B) of the Wheatstone bridge (8) and wherein an adjustable resistor (11) is connected in parallel between the two torsion-sensitive gages (9, 10) and with one (C or D) of the terminals for measurement of the Wheatstone bridge signal.