An agricultural baler (70) comprises a shaft (3), a flywheel (2) connected to the shaft (3), and a disc brake system (40) comprising a brake disc (41) with a toothed rim (59) for engaging with an auxiliary motor (5). The brake disc (41) may be directly mounted on the flywheel (2). The baler may have a brake controller for controlling the disc brake system (40), and a motor controller for controlling the auxiliary motor (5), or an integrated baler controller (56) for controlling both. The auxiliary motor (5) may be arranged for rotating the flywheel (2) forward or backwards.
