A mobile viscous matter pump comprising a hydraulically operated support construction, a distribution boom (16) and a pneumatic cushioned trailing axle (42). To ensure stability during the pump operation, the trailing axle (42) can be lifted by means of a lifting element (58) by bleeding the pneumatic suspension, whereby the bleeding of the pneumatic suspension (44) and the operation of the lifting element (58) and a locking element (64) can be controlled according to the on-condition of the auxiliary drive (NA) of the vehicle motor, used to supply the hydraulic fluid of the drive hydraulics.