Abstract: A theorem and method for determining the weight and center of gravity of a ground-engaging implemented connected to a three-point hitch on an agricultural tractor or other prime mover using hitch cylinder pressure and hitch position as calibration inputs to a hitch control system.

Abstract: A draft load control system for an agricultural tractor having electronic engine and draft load controllers interconnected by a digital communications bus over which parameters for engine load are made readily available to the draft load controller. The draft load control system is suitable for front-mounted, rear-mounted, or towed implements without requiring additional sensing equipment.

Abstract: The control includes a fluid system having a fluid passage in connection with a rod end chamber and a piston end chamber of a fluid cylinder connected to the front axle and a front end of a vehicle and extendible in length for increasing a distance between the front axle and the front end, a progressive control valve is disposed in the passage and is controllably movable through a range of progressively more restrictive partially open positions. The valve can also have a one-way flow position to allow fluid flow only from the piston end chamber to the rod end chamber, to allow only retraction of the cylinder. A controller is automatically operable for causing the valve to move through the range of progressively more restrictive partially open positions as the fluid cylinder is increasingly extended, and for moving the valve to the one-way flow position when the cylinder reaches a predetermined length.