Abstract: A mowing machine has a plurality of drive housings that are associated with the cutting units. Each unit has a carrying shaft that rotates a carrying unit which includes a carrying arm, cutting blades, and a covering disc. The carrying shaft is connected by gearing, located within the sealed drive housing, to the mowing machine's drive shaft. When the machine is in operation, the resulting friction within the drive housing causes the lubricants and air therein to expand. A channel is provided in the carrying shaft that opens at its lower end into the drive housing and at its upper end at the top of the carrying shaft under a conically configured cup spring, into a space which is not sealed from ambient pressures. The channel thus functions as a pressure vent to the otherwise sealed drive housing and permits the lubricants and air therein readily to expand and contract.