A method and vehicle traction system (1) comprising; - a first traction wheel (2a) forming part of a first propulsion system (12) comprising a mechanical drive train, - a second traction wheel (6a) forming part of a second propulsion system (13) comprising a hydraulic pump (7) for powering a hydraulic motor (8a), - one sensor (10a, 10b, 10c, 14) indicating a take-off condition, - a control unit (9) for controlling said second propulsion unit (13), wherein said control unit is programmed to; - automatically detecting a take-off condition by said sensor (10a, 10b, 10c, 14) and sending an input to the control unit (9) that a take-off condition is fulfilled, - automatically provide a traction force from said second propulsion system (13) in response to the indication that there is a take-off condition of the vehicle present and an indication that a traction is or will be provided by the first traction system, - automatically controlling said second propulsion unit (13) by the control unit (9) in dependence of the manually controlled torque from the first propulsion unit (12).