Patent ID: 7979188

Claim:
A method of activating and deactivating a four-wheel drive of one of a service and a working vehicle without interactive differential locks, the method comprising the step of: activating and deactivating the four-wheel drive depending on at least one of: a driving condition of the vehicle; and a load condition of the vehicle, derived using an output torque of a gearbox of the vehicle; activating the four-wheel drive when at least one of a vehicle speed drops below a first predetermined speed threshold value (v_ 1 ), and the gearbox output torque rises above a first predetermined torque threshold value (T_Ab 1 ), and deactivating the four-wheel drive when at least one of the vehicle speed rises above a second predetermined speed threshold value (v_ 2 ), and when the gearbox output torque drops below a second predetermined torque threshold value (T_Ab 2 ), where the second predetermined speed threshold value (v_ 2 ) is larger than the first predetermined speed threshold value (v_ 1 ) and the second predetermined torque threshold value (T_Ab 2 ) is smaller than the first predetermined torque threshold value (T_Ab 1 ).