some stock pickers have speed reduction or cutout when steering is turned past 10 or 15deg.
This can be either controlled by sensors on older units on the mdu or if mdu has position sensor pot it is controlled by a setting in the contoller/manager, it can be turned on or off if it is this.
This function is used mainly when running in aisles in racks, this is to keep trucks from taking out racking if steering is turned too far out of straight ahead travel.