| 摘要 |
A four-wheel steering system includes a frame that carries an axle that rotationally mounts a pair of front wheels via a pair of front pivotal wheel support assemblies. For steering, the front pivotal wheel assemblies are pivotal with respect to the axle. The frame also carries a pair of rear wheels that are rotationally mounted to the frame via a pair of rear pivotal wheel support assemblies. For steering, the rear pivotal wheel assemblies are pivotal with respect to the frame about vertical axes. The front pivotal wheel support assemblies are connected together by a front axle tie rod. Steering by an operator causes expansion or contraction of a hydraulic cylinder arranged between one front pivotal wheel support assembly and the axle, causing selective pivoting of both front pivotal wheel support assemblies. A linkage assembly is operatively connected between one of the front pivotal wheel assemblies and the rear pivotal wheel support assemblies to transform pivoting motion of the front pivotal wheel support assemblies to pivoting motion of the rear pivotal wheel support assemblies in a direction opposite to the pivoting motion of the front pivotal wheel support assemblies.
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