Many thanks for your reply, the steering is heavy and the rear wheels go out of line with the fronts and the machine crab steers, there is no adjustment to the rams they are set, when two wheel steer is selected its fine it steers in a straight line.
I have replaced all three of the change over valves which are located under the drivers floor
Would you consider the orbital steering box, or the steering hydo pump be at fault, low pressure etc?
Do you know were I may obtain a work shop manual, or a drawing of the hydraulic steering system?