supply of surface hardness testing instrument for rail grinding machine. , surface hardness testing instrument for rail grinding machine.it measures hardness before and after grinding having measuring accuracy (+/-) 4 hld/hldl (0.5% @800 hld/hldl), operating atmos pheric temperature should be -15 degree celsius to +50 degree celsius) and humidity max. 90, resolutio n 1 hl (leeb), 1 hv (vickers) , 1 hb (brinell), 0.1 hrc (rockwell), 0.1 hrb, 0.1 hs (hardness conversion s cales), hardness results in hlx are often converted to the traditional hardness scales hrc, hb and hv, wit h power input through usb.testing range 150-950 hld 250-970 hldl (native scale). [ warranty period: 30 months after the date of delivery ] ]