Operational Information

Semi Built Crankshaft Photographs



The following photographs show the manufacture of a semi built crankshaft from steel billets through to finished item. See also the 2 stroke engine crankshaft

I am indebted to Marco Erazo for some of the photographs.


The steel billets that form the crankthrows are lifted and placed in a furnace where they are heated to white heat.

The crankthrow is formed by forging the billet using hydraulic presses.


Re heating the billet between forging


Hydraulic presses form the crankthrow by squeezing the billet into a die


The partly forged crankthrow is removed from the die before reheating and moving on to the next forging press.

Partially forged crankthrows


Finished forgings after stress relieving and ageing ready for machining.


The holes for the main journals have been bored, the faces of the crankwebs are being machined.


Machining crankthrows.

Finish machined crankthrows


Vertical shrink fitting the crankthrows to the main journals.

Horizontal shrink fitting the crankthrows to the main journals.



Crankshaft in lathe for machining.

Crankshaft in lathe for machining.




Finished Crankshaft on Stand.


Close up showing chain wheels incorporating thrust collar and flywheel.

Close up showing collar on shaft for axial thrust damper.


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