Powertrain for trenching machine

A trenching machine includes a vehicle, an engine transmission assembly, a transfer box assembly, an elevated differential gearbox, a trenching chain drive shaft, a pair of roller chains engaging the trenching chain drive shaft and the output shaft of the differential gearbox, a trenching chain assembly mounted on and driven by the trenching chain drive shaft; and a discharge conveyor positioned below the differential gearbox and the pair of roller chains. The transfer box assembly, which transfers power from the engine transmission assembly vertically to the elevated differential gearbox, includes a sealed but accessible housing, a lower shaft, an upper shaft positioned parallel to and vertically above the lower shaft, and a roller chain running on sprockets on the upper and lower shafts. The lower shaft is connected to the engine transmission output shaft by a first universal joint, while the upper shaft is connected to the input of the differential gearbox by a second universal joint. Each of the upper and lower shafts is supported by a pair of roller bearings mounted in bearing housings, with one set of bearing housings having offset bores in which the roller bearings are mounted so that the distance between the shafts can be varied by rotating that set of bearing housings.