An inside gauge for checking the distortion of webs on crankshafts. With these gauges it is possible to check bearing alignments or deflections of the shaft without having to dismantle the engine. Usable on diesel engine shafts as well as center crankshafts of engines or compressors. Can also be applied as a strain gauge on engine frames while the engine is in operation. Indicator is graduated in increments of 0.01 mm with a reading of 0 – 50 – 0 one turn equals 1 mm. 6 rods and one extension are included providing a range of sizes from 100 to 500 mm.