Device 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 (S), 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 (S) 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 (S), 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 (S) in response to the demand in compressed air. <EOS>