GB714164A - Improvements in or relating to portable hardness testing instruments - Google Patents

Abstract

714,164. Testing physical qualities of materials. POCKNEE, J. K. July 2, 1952 [July 10, 1951], No. 16362/51. Class 106 (2) In a hardness testing instrument of the kind having an indenting tool 40 passing through an apertured anvil face of the .instrument and loaded through means acting on a substantially incompressible fluid in a fluid chamber 10 connected to a pressure gauge 12, a measuring means 60 actuated by the displacement of the indenting tool is adjustable to zero whilst the indenting load is zero. As shown, movement of the measuring tool 40 is transmitted to a 'clock gauge 60 through a pivoted lever 50. The lever 50 is. pivoted on a rod 53 vertically adjustable through the medium of a screw-jack mechanism 70. Two pivot holes 55, 56 are formed in the lever 50 to give a 1:1 or a 2: 1 ratio of the lever arms 57 to 47. In operation the apparatus is clamped to the specimen 96 under test by a U-shaped clamp 90, A screw-jack 14 is then operated to compress the fluid in the chamber 10 causing the tool 40 to be loaded through a spring 77 between the chamber 10 and the tool 40 and then directly to. the tool 40 when the spring 77 is sufficiently compressed to allow, the mainstem 35 of the indenting tool 40 to be brought into abutting engagement with the lower wall 43 of the chamber 10. At this stage the pressure gauge 12 and the dial gauge 60 are adjusted to zero. A further downward movement' of the tool 40 causes the instruments 12 and 60 to give pressure and displacement readings, from which the hardness of the material under test may be deduced. Specification 712,500 is referred to.