A brake pressure modulator , comprising: - a relay valve for controlling a supply of pressurized air from a primary source (II) to at least one brake actuator ; - a first valve sub-unit configured to be electronically actuated, wherein the first valve sub-unit is configured to receive a primary control pressure from the primary source (II) intended for opening the relay valve ; and - a second valve unit configured to at least receive a secondary control pressure from a secondary source ("BST") and at least part of the primary control pressure from the primary source (II) and to transmit either the primary control pressure or the secondary control pressure to the relay valve , wherein, when the secondary control pressure is transmitted to the relay valve , the primary control pressure from the primary source (II) is disconnected, and/or when the primary control pressure is transmitted to the relay valve , the secondary control pressure from the secondary source (BST) is disconnected, wherein the second valve unit is a mechanically operable valve, in form of a pneumatically controlled valve having a valve casing , characterized in that , the valve casing comprises - a pressurized guiding sleeve (304.4) providing a valve chamber configured to axially guide a pressure pickup piston or the like spool adapted for pneumatic actuation thereof, in particular adapted for mere pneumatic actuation thereof, and - a coil casing (304.5) configured to provide a coil chamber peripheral next to the pressurized guiding sleeve (304.4), wherein the valve chamber is free of a spring and the coil chamber is free of a coil or the like solenoid , such that the spool is actuable pneumatically only, in particular wherein the spool is subject to a pneumatic force only due to pneumatic pressure in the valve chamber . - a relay valve for controlling a supply of pressurized air from a primary source (II) to at least one brake actuator ; - a first valve sub-unit configured to be electronically actuated, wherein the first valve sub-unit is configured to receive a primary control pressure from the primary source (II) intended for opening the relay valve ; and - a second valve unit configured to at least receive a secondary control pressure from a secondary source ("BST") and at least part of the primary control pressure from the primary source (II) and to transmit either the primary control pressure or the secondary control pressure to the relay valve , wherein, when the secondary control pressure is transmitted to the relay valve , the primary control pressure from the primary source (II) is disconnected, and/or when the primary control pressure is transmitted to the relay valve , the secondary control pressure from the secondary source (BST) is disconnected, wherein the second valve unit is a mechanically operable valve, in form of a pneumatically controlled valve having a valve casing , characterized in that , the valve casing comprises - a pressurized guiding sleeve (304.4) providing a valve chamber configured to axially guide a pressure pickup piston or the like spool adapted for pneumatic actuation thereof, in particular adapted for mere pneumatic actuation thereof, and - a coil casing (304.5) configured to provide a coil chamber peripheral next to the pressurized guiding sleeve (304.4), wherein the valve chamber is free of a spring and the coil chamber is free of a coil or the like solenoid , such that the spool is actuable pneumatically only, in particular wherein the spool is subject to a pneumatic force only due to pneumatic pressure in the valve chamber . <EOS>