Alternators V Dynamos

[JAHetfield]

First off, apologies as this is a tractor related question but I figured this would be the best forum to post it in.

My tractor (Ford 4000 Force) wasn't charging the battery. I narrowed it down to a duff alternator so sourced a replacement and stuck it on. It wasn't a straight fit, I had to twist the top of it round to get the brackets to line up, this got me thinking that something wasn't right.

I have since learned that these tractors came with dynamos fitted and the alternator was something someone had been stuck on at a stage.

The tachometer also doesn't work but I have been told this is because it takes a feed from the alternator which isn't on the dynamo.

So what are the benifits of using an alternator over a dynamo?

[V8 FOU]

Loads of advantages. Much higher current. The best a dynamo can do is about 20A, whereas an alternator can do anything up to 100A. The alternator will charge at lower revs - it will even charge at tickover, a dynamo needs plenty of revs.
Having said that, old style alternators like the Lucas Ac11 etc aren't a lot better than a dynamo. I had some old CAV alternators on my boat and they were uselss. It now has 2 decent new ones!

[varsas]

JAHetfield said:

The tachometer also doesn't work but I have been told this is because it takes a feed from the alternator which isn't on the dynamo.

That will be the 'W' terminal (if you have one, not all do).