| 摘要 |
A swather tractor has a pair of driven ground wheels at one end where a header is supported and a pair of steerable wheels at the other end for 5 supporting the tractor. The driven ground wheels are hydraulically driven so that an operator controlled steering control is arranged to control a differential in rate of supply of hydraulic fluid to control a relative speed of rotation of the driven wheels and thus a turning direction of the tractor. The steerable wheels have a steering system that is operable in response to the steering control to positively steer the 10 steerable wheels and there is provided an arrangement to deactivate the steering system at large turns so that the steerable wheels are free to castor. r- - - |
