| 摘要 |
PROBLEM TO BE SOLVED: To make a vehicle swivel in response to the state of ground by forcefully changing into rear 2WD state when it is swiveling and by determining the braking force for a inside rear wheel of swiveling according to the revolution ratio between front and rear wheels when a predetermined time elapses from setting. SOLUTION: When a selector switch for 4WD is on and it is judged that a vehicle body starts rotation from a steering angle sensor 17, braking force is set for a inside rear wheel of swiveling based on a judgement when the vehicle is driven straight-ahead and a preferable driving mode is selected. When a given time elapses, the driving mode is forcefully changed to rear 2WD state and thereafter revolution ratio between front and rear wheels is calculated from detected data of a front wheel rotation sensor 46 and a rear wheel rotation sensor 45 and then the following braking force of the inside rear wheel of swiveling and driving mode is determined based on the difference between the calculated revolution ratio and a standard revolution ratio; for example, when the vehicle is rotating on a hard field such as dried paddy or unculivated field, braking pressure is set HIGH and driving mode is set in rear 2WD state.
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