from The Century Dictionary.
- Having three cranks on one shaft: an arrangement used with engines or pumps having three cylinders to secure even distribution of turning effect, or, in pumping liquids, a steady flow from the pumps.
Sorry, no etymologies found.
It may be mentioned that in these two ships the engines are of a similar type, being three-crank tandem engines, and the propellers have in both pitch and surface practically the same proportions to the power and speed.
He should recommend the adoption of a three-crank six-cylinder engine.