An agricultural machine includes a cutting mechanism and first and second conditioning elements driven by a transmission comprising a primary box including a first output connected to the cutting mechanism, a second output connected to the first conditioning element and a third output, connected with one another by primary transmission means, the transmission including a secondary box including an input connected to the third output and an output connected to the second conditioning element, connected with one another by secondary transmission means, the transmission comprising a lubrication device for the primary box with a pump and a primary distribution system for a lubricant towards the primary transmission means. The lubrication device comprises a secondary distribution system distributing the lubricant from the pump towards the secondary transmission means, and a return system for the lubricant from the secondary box towards the pump.