An agricultural system comprising: an agricultural baler comprising: a rotary input shaft connectable by way of a baler driveline to a rotatable flywheel; a hydraulic pump for supplying the agricultural baler with hydraulic fluid, the rotatable flywheel being connectable to the hydraulic pump via the driveline, wherein the baler is transferrable between a first state for driving the hydraulic pump by means of external drive power provided by a work vehicle, and a second state for driving the hydraulic pump by means of internal drive power provided by means of the rotatable flywheel, a control unit that is configured to: receive input power data indicative of drive power available for driving the hydraulic pump in the first state of the baler; and determine a control signal for transferring the baler into its second state, if the input power data indicates that the available drive power is insufficient for driving the hydraulic pump, characterised in that the driveline includes a transmission including driveline components defining at least first and second selectable transmission ratios (G1, G2) between the input shaft and the flywheel, wherein, in the first state of the baler, the first transmission ratio is a reduction ratio and the second transmission ratio is an acceleration ratio, and wherein, in the second sate of the baler, the first transmission ratio is an acceleration ratio and the second transmission ratio is a reduction ratio. an agricultural baler comprising: a rotary input shaft connectable by way of a baler driveline to a rotatable flywheel; a hydraulic pump for supplying the agricultural baler with hydraulic fluid, the rotatable flywheel being connectable to the hydraulic pump via the driveline, wherein the baler is transferrable between a first state for driving the hydraulic pump by means of external drive power provided by a work vehicle, and a second state for driving the hydraulic pump by means of internal drive power provided by means of the rotatable flywheel, a rotary input shaft connectable by way of a baler driveline to a rotatable flywheel; a hydraulic pump for supplying the agricultural baler with hydraulic fluid, the rotatable flywheel being connectable to the hydraulic pump via the driveline, wherein the baler is transferrable between a first state for driving the hydraulic pump by means of external drive power provided by a work vehicle, and a second state for driving the hydraulic pump by means of internal drive power provided by means of the rotatable flywheel, a control unit that is configured to: receive input power data indicative of drive power available for driving the hydraulic pump in the first state of the baler; and determine a control signal for transferring the baler into its second state, if the input power data indicates that the available drive power is insufficient for driving the hydraulic pump, characterised in that the driveline includes a transmission including driveline components defining at least first and second selectable transmission ratios (G1, G2) between the input shaft and the flywheel, wherein, in the first state of the baler, the first transmission ratio is a reduction ratio and the second transmission ratio is an acceleration ratio, and wherein, in the second sate of the baler, the first transmission ratio is an acceleration ratio and the second transmission ratio is a reduction ratio. receive input power data indicative of drive power available for driving the hydraulic pump in the first state of the baler; and determine a control signal for transferring the baler into its second state, if the input power data indicates that the available drive power is insufficient for driving the hydraulic pump, characterised in that the driveline includes a transmission including driveline components defining at least first and second selectable transmission ratios (G1, G2) between the input shaft and the flywheel, wherein, in the first state of the baler, the first transmission ratio is a reduction ratio and the second transmission ratio is an acceleration ratio, and wherein, in the second sate of the baler, the first transmission ratio is an acceleration ratio and the second transmission ratio is a reduction ratio.