end of dynamo. what is missing

[andrew34ruby]

Thanks everyone, all help appreciated. It is a dynamo I have just assembled, everything seems to be back together properly with the gear properly on the shaft on the woodruff key. I struggled to find a nut the correct thread and the one fitted is rather 'thick'. The intention is to apply grease before fitting the end cap, but in the pile of bits from two dismantled dynamos I cannot find an end cap -- hence the question.

Ah, no spring washer. Considered wisdom on various engineering websites conclude that spring washers do not work and any washer tends to helps things to come undone. https://engineerdog.com/2015/01/11/10-tr...fasteners/

Now that I know what it should be, I'll see if I can make a deeper welch plug, domed enough to go over this nut.