Abstract: The invention describes a device for controlling the tension of a web discharged from a delivery spool including a compensating roller around which the web is guided to which a tiltingly supported lever is connected the deflection of which influences a pneumatic valve, which provides, in a compressed-air line system including a reduction valve, for the pneumatic pressure of a brake cylinder of a pneumatic brake of a machine processing the web, wherein the lever 4 is engaged by a tension spring with adjustable stroke and the lever is tiltable between two end switches 10, 11, which actuate valves including series-connected reduction valves 14, 15 inserted into one pneumatic line 12, 13 each, both being connected to a compressed-air tank 19 which actuates the brake cylinder 22, the valve actuated in case of a decrease of the tension of the web 1 being inserted into the line under pressure 12 and when actuated by the lever 4 connecting the compressed-air tank 19 to the compressed-air source 15a, and the valve act