Method for controlling the traction of a pneumatically sprung vehicle and air suspension system for carrying out the method

An air suspension system (36) for a vehicle (1), having at least one front steering axle (A), at least one rear drive axle (TA) and a trailing axle (SA) in front of or behind the drive axle (TA), comprising

• an electronic control and regulation unit (7), an operating unit (8) configured to be actuated by a vehicle driver and which is connected to the electronic control and regulation unit (7), a valve block (9) which is connected to the electronic control and regulation unit (7) and which has multiple switching valves (16, 19, 22, 25), and in each case one pressure sensor (S2, S4;
• S3, S5), connected to the electronic control and regulation unit (7), at each of the supporting bellows (2, 4;
• 3, 5) of the at least one drive axle (TA) and of the trailing axle (SA), each of the multiple switching valves (16, 19, 22, 25) being connected to only one respective one of the supporting bellows (2, 4;
• 3, 5), wherein the electronic control and regulation unit (7) is configured to perform the following steps:
• in the regulation mode “pressure ratio regulation”, continuously automatically checking, on the basis of the present supporting bellows pressures, whether relieving the trailing axle (SA) of load is possible without thereby overloading the at least one drive axle (TA),
• upon determining that relieving the trailing axle (SA) of load is possible without thereby overloading the at least one drive axle (TA), automatically switching into a regulation mode “optimum traction”, and
• in the regulation mode “optimum traction”, increasing the pressure in the supporting bellows (2, 4) of the at least one drive axle (TA) by actuating the switching valves of the valve block (9), and decreasing the pressure in the supporting bellows (3, 5) of the trailing axle (SA) to a parameterized residual pressure, in order to thereby effect a load shift to the at least one drive axle (TA) by relieving the trailing axle (SA) of load without exceeding a maximum admissible axle load of the at least one drive axle (TA) and without undershooting a minimum admissible axle load of the trailing axle (SA).