To properly transfer axle load between the two rear axles of a two- rear-axle vehicle without being affected by a loaded state, or the like the axle load distribution between the two rear axles being controlled according to live load.
When a two-rear-axle vehicle is vacant, for example, compressed air is fed from a tank 10 through a first magnet valve M1 opened and closed by a controller 20 to an air spring 8 working in the direction in which a driven rear rear axle is lifted, and thereby the desired air pressure is held within the air spring 8 to make the axle load of a driving rear front axle greater than that of the driven rear rear axle by an appropriate amount, so that the desired axle load of the driving rear front axle relative to the vehicle total weight detected by a front axle load sensor 23 and a rear axle load sensor 24 can be attained all the time.
WATANABE TOMOYASU
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