The invention relates to a shaft drive unit, in particular an electrical drive unit for driving a wheel shaft in vehicles; having an electrical machine comprising a rotor and a stator; having a transmission unit, comprising at least one input connected in a rotationally fixed manner to the rotor of the electrical machine, and at least one output connected in a rotationally fixed manner to the wheel shaft. The electrical machine, the input and the output of the transmission unit and the wheel shaft are arranged coaxially with respect to one another. The electrical machine has at least one associated converter unit and one associated braking resistor unit. The converter unit forms a physical unit with the electrical machine. The braking resistor unit is arranged in the immediate physical vicinity of the electrical machine and around the circumference of the input or output drive shaft of the electrical machine or of the wheel shaft.