PUMPING UNIT EQUIPPED WITH OSCILLATING HYDRAULIC PRESSURE INTENSIFIER FOR CYLINDERS WITH SMALL OVERALL SIZES AND LARGE LOADS THROUGHOUT THE STROKE

Abstract

Conveyance of goods and travelling of persons through the tunnels of mines or subway is done on railways of narrow or normal gauge. In interventions in case of accidents, hydraulically operated installations with small dimensions are used for lifting and rerailing the derailed rolling stock. They include hydraulic jacks (double or single acting hydraulic cylinders), supplied with low flow rates at high pressures. Feeding of hydraulic cylinders for lifting and relocating the derailed rolling stock is usually done by means of high-pressure pumps, manually operated or driven by electric / thermal motors. The authors propose the use of a more cost-effective pumping unit with low-pressure pump and oscillating hydraulic pressure intensifier for this kind of applications - and for similar ones that involve interventions in narrow workspaces. Such pumping units are usually used in applications designed to achieve and maintain high pressures, either in the volumes of enclosed spaces (endurance tests for pipes and tanks) or at the active stroke end of hydraulic cylinders (hydraulic presses). The authors demonstrate, on an experimental test bench, that the displacement of a highpressure hydraulic cylinder, with constant load over the entire stroke, can take place safely even if a low-pressure pumping unit, equipped with oscillating hydraulic pressure intensifier powers it.