GB1389680A - Hydraulic testing machine - Google Patents

Abstract

1389680 Hydraulic testing machine CARL SCHENCK AG 20 Dec 1972 [27 Jan 1972] 58877/72 Heading G1S A known hydraulic testing machine comprises a piston and cylinder for producing a static preload, a further piston and cylinder for producing a dynamic alternating load, and pressure reservoirs connected to the pre-load cylinder above and below the piston to prevent pressure surges. When operating slowly however, by producing a slowly varying test load by means of the pre-load cylinder, the reservoirs produce an undesirable disturbing effect. The invention seeks to overcome this disadvantage by providing accumulator bags in the reservoirs connected to other pressure reservoirs or pressure raisers in order to vary the pressure in the original reservoirs by emptying them partially or completely. In Fig.1, the pre-load pressure cylinder 1 and piston 2 are connected to reservoirs 3, 4 containing gas filled accumulator bags fed by gas bottles 5, 6 via gauges 9, 10 and valves 7, 8, and the cylinder I is also connected by a hydraulic switch valve 12 to a hydraulic assembly 11 providing additional pressure. By means of the gas bottles and the hydraulic supply 11 the pressure in cylinder 1 may be controlled by increasing or decreasing the pressure in the accumulator bags to expand or contract them and shunt the hydraulic fluid into or out of the reservoirs and the cylinder 1. The pressures in 3 and 4 may be held at different values by closing the valves 7, 8 at different times so that the desired pre-load may be applied in cylinder 1. In Fig.2 (not shown) the bag pressures are produced by a pressure raiser (14) driven by mains compressed air and fed from a bottle (5). In Fig.3 (not shown) additional reservoirs and accumulator bags in series are provided.