Patent GB-537933-A (GB)
Title: Improvements in hydraulic testing machines
IPC: G01N3/10
Filed: 1940-03-01
Abstract: 537,933. Testing physical qualities of materials. AVERY, Ltd., W. & T., and YATES, H. March 1, 1940, No. 3836. [Class 106 (ii)] Comprises a hydraulic testing machine wherein a plurality of differential ram cylinders are interposed between the hydraulic straining unit and an indicating mechanism having several ranges proportional to each differential ram capacity, the rams being inter-connectible and the cylinder pressure being communicated to the load resistant which is connected to an indicating pointer. The straining unit A is of known kind incorporating a main cylinder 5 between crossheads 6, 7 connected to upper and lower grip holders 8, 9 respectively. The plunger 10 of the cylinder 5 is connected to the crosshead 6 while the cylinder is connected to the crosshead 7. The unit A is coupled through pipes and links to the load transmission and resistant mechanism and to indicating mechanism located together in a housing B which also contains the pump unit. The cylinder 5 is connected by a pipe 11 with a mechanism 12 having a dial provided with a plurality of concentric charts of different load ranges over which moves a pointer 13 associated through rack and pinion 15, 16 with a resistant in the form of a pendulum 14. Ram cylinders 17 of different capacity having a pre-determined ratio to the cylinder 5 are connected to the pendulum 14 so that the power factor remains the same for all ranges. Pressure is applied to the cylinder 5 and the pre-selected cylinder 17 by means of a motor-driven duplex oil pump 19. The cylinders 17 are arranged co-axially one above the other so that any one ram may be brought into contact with the next and coupled thereto by a dog clutch. The rams are rotated slowly to avoid friction by an auxiliary motor 22 carried on a yoke 23 to which the straining force applied through the cylinders is communicated by a ball-thrust from the lowest cylinder. The yoke 23 is suspended by rods 25 connected to an upper yoke 26 in turn connected by linkage 27 to a crank 28 on the spindle 29 of a pedulum 14. The differential cylinder assembly is supported from a crosshead 17a on pillars 52 supported from a base cross member 53. Since the same weight 14 is used for all scales, the zero of pointer 13 must be set prior to any test. This is done by moving arms 14b on the shaft 29 by adjustment of a worm-screw rack 15 which meshes with a pinion 16 on the pointer spindle and at the end 15a engages the arm 14b. A parallel rod 32 sliding with rack 15 carries an adjustable contact stop 33 which when it meets switch 34 at maximum load stops the pump. A weight 35 forming part of a dash pot urges the rack 15 into contact with the arm 14b. Movement of handle 21 rocks a lever 39 which through flexible connection 40 starts the lowpressure pump circuit until the head 8 is positioned for insertion of the specimen. The lever 24 is next operated and through linkage opens the high-pressure pump circuit to cylinder 5. Upon completion of a test the lever 21 is reversed and the connection 40 releases the cylinder 5 to atmosphere. The pipe line 11 extends into a four-way valve chamber 11a from which pipes extend to the cylinders 17. A maximum load pointer 13a is fitted. The rate of straining is controlled by a knob 43 and valve operating connections 46, 47, 48.