Hydrostatic transmission and shift control method

A hydrostatic gearbox (62) with a variable transmission ratio links to a secondary gearbox (8) that has two gear speeds and connects to a driven shaft (7) in the hydrostatic gearbox, which in turn has a hydraulic pump (4) and a hydraulic motor (6) connected to the hydraulic pump by hydraulic operating pipes (5a,5b). An adjusting device (13) can adjust a pivoting angle for the hydraulic motor. An Independent claim is also included for a method for changing gears in a gearbox as secondary transmission to hydrostatic gearing.