Device (1000, 1000') for mixing and conveying thick matter, comprising: - a main supply voltage connection, - a main electric motor which is electrically connected to the main supply voltage connection, - a main hydraulic pump, wherein the main hydraulic pump is driven by means of the main electric motor and feeds a mixer hydraulic circuit and a compressed air hydraulic circuit, wherein the main hydraulic pump is arranged, in response to a control signal, to vary a ratio of a power fed into the mixer hydraulic circuit to a power fed into the compressed air hydraulic circuit, - a hydraulic mixer drive which is fed from the mixer hydraulic circuit, wherein the hydraulic mixer drive is provided for mixing the thick matter, - a hydraulic compressor drive which is fed from the compressed air hydraulic circuit, wherein the hydraulic compressor drive is provided for generating compressed air, - an auxiliary supply voltage connection, - an auxiliary hydraulic system, comprising: - an auxiliary electric motor which is electrically connected to the auxiliary supply voltage connection and is operable independently of the main electric motor, and - an auxiliary hydraulic pump, wherein the auxiliary hydraulic pump is driven by means of the auxiliary electric motor, and - a controller device which is arranged, in response to a demand in compressed air, to control the auxiliary hydraulic system such that the auxiliary hydraulic pump feeds the compressed air hydraulic circuit in addition to the main hydraulic pump, and wherein the controller device is arranged to generate the control signal in response to the demand in compressed air. - a main supply voltage connection, - a main electric motor which is electrically connected to the main supply voltage connection, - a main hydraulic pump, wherein the main hydraulic pump is driven by means of the main electric motor and feeds a mixer hydraulic circuit and a compressed air hydraulic circuit, wherein the main hydraulic pump is arranged, in response to a control signal, to vary a ratio of a power fed into the mixer hydraulic circuit to a power fed into the compressed air hydraulic circuit, - a hydraulic mixer drive which is fed from the mixer hydraulic circuit, wherein the hydraulic mixer drive is provided for mixing the thick matter, - a hydraulic compressor drive which is fed from the compressed air hydraulic circuit, wherein the hydraulic compressor drive is provided for generating compressed air, - an auxiliary supply voltage connection, - an auxiliary hydraulic system, comprising: - an auxiliary electric motor which is electrically connected to the auxiliary supply voltage connection and is operable independently of the main electric motor, and - an auxiliary hydraulic pump, wherein the auxiliary hydraulic pump is driven by means of the auxiliary electric motor, and - an auxiliary electric motor which is electrically connected to the auxiliary supply voltage connection and is operable independently of the main electric motor, and - an auxiliary hydraulic pump, wherein the auxiliary hydraulic pump is driven by means of the auxiliary electric motor, and - a controller device which is arranged, in response to a demand in compressed air, to control the auxiliary hydraulic system such that the auxiliary hydraulic pump feeds the compressed air hydraulic circuit in addition to the main hydraulic pump, and wherein the controller device is arranged to generate the control signal in response to the demand in compressed air.