Trailer for harvester header

A trailer for transporting a harvester header comprises a chassis (16), a rear axle assembly (20) and a front axle assembly (24). Steering force transfer means are arranged to transfer a steering force hydraulically from a first one steerable wheel (26) supported on the front axle assembly to a second one steerable wheel (22) supported on the rear axle assembly. A steering movement of the first one steerable wheel to one side effects a steering movement of the second one steerable wheel to the opposite side.