Gear Teeth Portable Hardness Tester/Long Nose Portable Hardness Testers. Features. Same features as 1800 but with DL impact device. Portable Hardness Tester specializing in testing large hard metal parts in confined spaces. This dedicated unit is designed to test gear teeth and other difficult to access applications. The 1840 is loaded with the same features found on the base 1800 version which includes memory, USB output and software for downloading to your PC. The 1840 hardness tester is capable of measuring the surface hardness of a broad variety of metals on flat and round surfaces. This instrument comes complete with a dedicated DL impact device, calibrated test block and rugged carry case. Designed to test large hard parts: Example: Tool steel should be close to 1 thick of solid material. Options: NIST/ASTM certified hardness test blocks are available.