A control system for a tractor (1) which includes a transmission (T) with a hydraulic drive circuit in which a hydraulic pump (407) supplies pressurised fluid to a hydraulic motor, the control system controlling an operating condition of an implement (500), for example the position of an attachment hitch relative to the tractor (1) via an actuator means (403) which raises and lowers the implement hitch relative to the tractor (1). The system includes a pressure sensing means (411) to sense the pressure in the hydraulic drive circuit connecting the pump (407) and motor which is indicative of the current pull force necessary to pull the implement (500). The system also including a control means which receives the pressure signal and inputs from the tractor operator indicative of the required operating condition of the implement (500) and adjusts operating conditions such as the vertical position of the hitch (400) relative to the tractor (1) in response to the variations in the pressure signal in order to try to maintain the required operating condition of the implement (500).
