A device (10) and a method for locking a slewable arm of a machine (70), mountable on a vehicle (80). The device (10) comprises a foot (11), which can be securely connected to the vehicle: a slewing system (12), rotatable in relation to the foot, and drivable by a drive (20) to cause the machine to rotate； and locking means (30, 35) for locking the rotation of the slewing system (12) relative to the foot (11), wherein the locking means (30,35) are independent of the drive (20).
