Abstract: An apparatus and method of supplying feedwater to a forced flow boiler or the like as described. A positive displacement pump having a plurality of discrete pumping elements is arranged to pump feedwater from an inlet to the boiler. The pump includes bypass valves which, when open, disable the pumping action of an associated pumping element. Control means responsive to the demand for water in the boiler are arranged to disable a selected number of the pumping elements so that the rate of water supplied by the remaining elements, if operated continuously, would just exceed that required. The control means is further arranged to disable at least one of the remaining pumping elements on a periodic basis so that the ratio of time that the element is enabled to the time for one period multiplied by the water flow rate supplied by said element, if operated continuously, equals the difference between the total demand for water and the rate supplied by the pumping elements enabled on a full-time basis.

Abstract: Prior art electromechanical inertia and road load simulators as applied in dynamometers measure speed and acceleration, then compute and control torque--a relatively slow and inaccurate operation. This invention measures torque, then computes and controls acceleration and speed--a fundamentally different approach which provides faster action, more accurate simulation and closer repeatability. The simulator described herein includes and is controlled by a computer which is provided with inputs from a torque transducer, a speed encoder and operator entered digital signals. The computer then makes accurate and rapid computations of vehicle inertia, road load forces and generates an electrical speed control signal. This signal is provided to a controller for a power absorber, e.g., a direct current power controller which drives a direct current motor. The power absorber such as the motor is mechanically coupled to the vehicle engine or a rotating roll upon which a test vehicle drive wheel rests.