Air motors which are affordable at list price
are extraordinarily inefficient in terms of the quantity of air they waste.
If anyone wants to try the suggestion to make an emergency
starter using components, please consider spending not much more for a pre-owned (or even "new old stock", reputable brand-name motor
. There is a brief window of opportunity; industrial activity is being outsourced eastwards, so there's a temporary glut.
If you go for Harbor Freight or similar, by the time you've compounded the losses by gearing it down (especially if, once again, you resort to HF-style engineering) you're likely to have shot your bolt for nothing.
Driving the flywheel is tricky, unless you plan to engineer
a starter pinion mounting and engagement mechanism, which is not for the fainthearted.
I would suggest it would be more promising to make up a large diameter V belt pulley, to bolt onto the front of the crankshaft pulley.
There needs to be some sort of one-way drive to prevent the diesel trying to drive the air motor
at high speed when it starts. Possibly use linkbelt to enable adjusting the belt tension without the need for a swinging mount (and to enable removing the belt when the emergency
starter is required)
Pay no heed to the prevailing culture on this forum. There appears to be a widespread belief that a problem which cannot be solved by them cannot be solved by us.
A slightly more sophisticated version is that if it cannot be solved by them it should not be solved by anyone -- other than large commercial
concerns or governments. The sailing community can then piggyback on their solution by opening their wallets - mission accomplished.
Like Tinkerbelle, these propositions are true for those believe in them: anything they think they cannot solve, they will not solve.
What I find disappointing about this is that due to the democracy of markets, eventually the resourceful minority will run out of raw material.
Given the dwindling demand for robust simple technology, like self-sufficient engines and pumps, the supply is drying up before our eyes, denying future sailors options taken for granted by our forebears.
The opportunity to travel the world in relative safety
without being lashed to the apron strings of corporations and states and airfreight companies is rapidly being extinguished.