Patent ID: 8770826

Claim:
A vertical mixer for mixing bulk material, the vertical mixer comprising: a mixing chamber defined by a floor and upending wall, the mixing chamber for receiving bulk material; a vertical auger for mixing the bulk material, the vertical auger including a hollow auger tube with flighting affixed thereto; a gearbox for driving the auger, the gearbox vertically mounted through the floor of the mixing chamber and including a top portion captured within the auger tube and a bottom portion extending below the floor, the gearbox comprising: an input interface for receiving power output from a power source; gearing in communication with the input interface; an output shaft in communication with the gearing for outputting power via the top of the gearbox to the auger; an oil lubricated bearing for guiding the output shaft; an internal oil reservoir in fluid communication with the gearing, the output shaft and the oil lubricated bearing wherein a minimum oil fill level at least covers the oil lubricated bearing; and a breather bore extending through the output shaft and exiting the top of the output shaft via a top port and exiting a side of the output shaft via a bottom port, the bottom port in fluid communication with the internal oil reservoir, wherein a maximum oil fill level is above the minimum oil fill level.