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Technical requirements of the crankshaft


1) The accuracy of the main journal and connecting rod journal, that is, the diameter dimension tolerance level is usually IT6 ~ IT7; the width limit deviation of the main journal is + 0.05 ~ -0.15mm; the limit deviation of the turning radius is ± 0.05mm; The limit deviation of axial dimension is ± 0.15 ~ ± 0.50mm.

2) The tolerance grade of journal length is IT9 ~ IT10. The shape tolerance of the journal, such as roundness and cylindricality, is controlled within half of the dimensional tolerance.

3) Position accuracy, including the parallelism of the main journal and the connecting rod journal: generally within 100mm and no more than 0.02mm; the coaxiality of the main journals of the crankshaft: 0.025mm for small high-speed engines, and for large and low-speed engines 0.03 ~ 0.08mm; the position of each connecting rod journal is not more than ± 30 ′.

4) The surface roughness of the connecting rod journal and main journal of the crankshaft is Ra0.2 ~ 0.4μm; the surface roughness of the connecting rod journal, main journal, and crank connection fillet of the crankshaft is Ra0.4μm.
In addition to the above technical requirements, there are regulations and requirements for heat treatment, dynamic balancing, surface strengthening, cleanliness of oil passage holes, crankshaft cracks, and crankshaft rotation direction.