The BDB system integrates in one machine the functions of a metering bunker and a continuous scale. Modifying the velocity of the belt it is possible to vary the dosing. The system guarantees a precision of +/-0,5%. The continuous scales are independent units and can be installed on new or pre-existing systems. The electronic device box supplied with the machine puts into relation the weight signal coming from the load cell with the real speed signal of the metering belt, coming from an encoder, in this way the instant and the total metering values are detected.