To prevent the generation of an inner wheel difference by a method wherein each truck is run on the same rail even when a plurality of trucks are intercoupled.

Front wheels 2 are interlocked with each other by a front wheel steering mechanism 14 comprising a steering member 19 consisting of a slide piece 16, a tuning shaft 4, a coupling tool 22, and a rotary lever 24, and connected to the steering member 19 and oscillated in the same direction as that of a steering lever 20. Rear wheels 3 are interlocked with each other through a rear wheel steering mechanism 15 comprising a steering member 21 consisting of a slider piece 17, a tuning shaft 5, a coupling tool 23, and a rotary lever 25 and oscillated in the same direction as that of the steering member 21. The front and rear wheel steering devices 14 and 15 are intercoupled and interlocked with each other through a violating mechanism 6, and front wheels 2 and rear wheels 3 are oscillated in a reverse direction symmetrically to each other.