A working machine comprising: a ground engaging structure; a propulsion system for moving the working machine via the ground engaging structure; a body supported on the ground engaging structure; a working arm connected to the body and having a carriage at one end for receiving an attachment; and a control system for selectively oscillating the carriage, wherein the control system comprises: an actuator (24, 26, 58) configured and arranged to selectively oscillate the carriage; an electronic controller configured to control the actuator (24, 26); and a user input device in communication with the controller; wherein the user input device comprises an oscillation input configured to selectively transmit an oscillation signal to the electronic controller to indicate a desired amplitude and/or frequency of oscillation of the carriage, wherein the oscillation input is variable to alter the oscillation signal transmitted to the electronic controller; and wherein the electronic controller is configured to upon receipt of the oscillation signal selectively activate the actuator (24, 26, 58) to oscillate the carriage at the desired frequency and/or amplitude indicated by the oscillation signal, and wherein the user input device comprises a position input configured to transmit a position signal to the electronic controller to indicate a desired change of position of the carriage, and wherein the position input comprises an input device that a user can move to indicate the desired change of position of the carriage, wherein the electronic controller is configured to upon receipt of the position signal activate the actuator (24, 26, 58) to move the carriage as desired, and the input device is configured such that the oscillation signal transmitted to the controller is dependent upon the position of the input device, characterised in that: the desired frequency of the oscillations indicated by the oscillation signal is proportional to the position of the input device with respect to a neutral position of the input device. a ground engaging structure; a propulsion system for moving the working machine via the ground engaging structure; a body supported on the ground engaging structure; a working arm connected to the body and having a carriage at one end for receiving an attachment; and a control system for selectively oscillating the carriage, wherein the control system comprises: an actuator (24, 26, 58) configured and arranged to selectively oscillate the carriage; an electronic controller configured to control the actuator (24, 26); and a user input device in communication with the controller; wherein the user input device comprises an oscillation input configured to selectively transmit an oscillation signal to the electronic controller to indicate a desired amplitude and/or frequency of oscillation of the carriage, wherein the oscillation input is variable to alter the oscillation signal transmitted to the electronic controller; and wherein the electronic controller is configured to upon receipt of the oscillation signal selectively activate the actuator (24, 26, 58) to oscillate the carriage at the desired frequency and/or amplitude indicated by the oscillation signal, and wherein the user input device comprises a position input configured to transmit a position signal to the electronic controller to indicate a desired change of position of the carriage, and wherein the position input comprises an input device that a user can move to indicate the desired change of position of the carriage, wherein the electronic controller is configured to upon receipt of the position signal activate the actuator (24, 26, 58) to move the carriage as desired, and the input device is configured such that the oscillation signal transmitted to the controller is dependent upon the position of the input device, characterised in that: the desired frequency of the oscillations indicated by the oscillation signal is proportional to the position of the input device with respect to a neutral position of the input device. an actuator (24, 26, 58) configured and arranged to selectively oscillate the carriage; an electronic controller configured to control the actuator (24, 26); and a user input device in communication with the controller; wherein the user input device comprises an oscillation input configured to selectively transmit an oscillation signal to the electronic controller to indicate a desired amplitude and/or frequency of oscillation of the carriage, wherein the oscillation input is variable to alter the oscillation signal transmitted to the electronic controller; and wherein the electronic controller is configured to upon receipt of the oscillation signal selectively activate the actuator (24, 26, 58) to oscillate the carriage at the desired frequency and/or amplitude indicated by the oscillation signal, and wherein the user input device comprises a position input configured to transmit a position signal to the electronic controller to indicate a desired change of position of the carriage, and