A combine harvester comprising : • a feeder at the front of the harvester, the feeder comprising a housing , an input section and an output section , • a driveline rotatably coupled to a power source of the combine and comprising a jackshaft in the vicinity of the input section of the feeder, • a combine header removably attached to a front portion of the feeder , and comprising a header driveline that includes a header drive shaft configured to be releasably coupled to the jackshaft , characterised in that the combine harvester comprises a mechanism for automatically coupling the header drive shaft to the jackshaft , said mechanism comprising : • a pendulum arm pivotably connected to the header at a first end, and arranged to pivot relative to the header , about a first pivot axis oriented transversely with respect to the jackshaft , • a bearing hub connected to the pendulum arm at a second, opposite end of the pendulum arm , the hub comprising a housing and a rotatable axle portion inside the housing and rotatable relative to the housing , wherein one end of the axle portion is rotatably connected to the header drive shaft , and an opposite end of the axle portion comprises a first part of an axial clutch, • an actuator mounted on the header and configured to actuate a pivoting motion of the pendulum arm about the first pivot axis , • a second clutch part configured to engage with the first clutch part , the second clutch part being mounted at an outer end of the jackshaft . • a feeder at the front of the harvester, the feeder comprising a housing , an input section and an output section , • a driveline rotatably coupled to a power source of the combine and comprising a jackshaft in the vicinity of the input section of the feeder, • a combine header removably attached to a front portion of the feeder , and comprising a header driveline that includes a header drive shaft configured to be releasably coupled to the jackshaft , characterised in that the combine harvester comprises a mechanism for automatically coupling the header drive shaft to the jackshaft , said mechanism comprising : • a pendulum arm pivotably connected to the header at a first end, and arranged to pivot relative to the header , about a first pivot axis oriented transversely with respect to the jackshaft , • a bearing hub connected to the pendulum arm at a second, opposite end of the pendulum arm , the hub comprising a housing and a rotatable axle portion inside the housing and rotatable relative to the housing , wherein one end of the axle portion is rotatably connected to the header drive shaft , and an opposite end of the axle portion comprises a first part of an axial clutch, • an actuator mounted on the header and configured to actuate a pivoting motion of the pendulum arm about the first pivot axis , • a second clutch part configured to engage with the first clutch part , the second clutch part being mounted at an outer end of the jackshaft . • a pendulum arm pivotably connected to the header at a first end, and arranged to pivot relative to the header , about a first pivot axis oriented transversely with respect to the jackshaft , • a bearing hub connected to the pendulum arm at a second, opposite end of the pendulum arm , the hub comprising a housing and a rotatable axle portion inside the housing and rotatable relative to the housing , wherein one end of the axle portion is rotatably connected to the header drive shaft , and an opposite end of the axle portion comprises a first part of an axial clutch, • an actuator mounted on the header and configured to actuate a pivoting motion of the pendulum arm about the first pivot axis , • a second clutch part configured to engage with the first clutch part , the second clutch part being mounted at an outer end of the jackshaft . <EOS>