Improvements in pumps for hydraulic gears, lifting machines, hydraulic presses and the like

摘要

255,869. Hardt, A. July 23, 1925, [Convention date]. Eccentric-actuated pumps; stroke-varying mechanism.-The delivery pressure of pumps used for supplying hydraulic gear, lifting-machine, presses, &c. is automatically controlled so that the delivery varies inversely as the delivery pressure whereby the load on the driving-motor is constant. A radial pump a has an eccentric track b the position of which is varied transversely by the delivery pressure. The track b is connected to pistons f, h on a common rod with a plunger extension o. The piston f is subject to delivery pressure, and the left-hand side of the piston h to air pressure supplied past a non-return valve m from a reservoir n. The pressure of air is to the pressure of the oil or liquid pumped at maximum delivery as the area of the piston f is to the area of the piston h. Variations in delivery pressure affect the track position until a balance is effected. Pressure may be supplied to the extension o under the control of a handcock r to reduce the load on the driving motor as, for example, when starting a motor car. The air mechanism may be replaced by a spring or weight acting through a cam.