Caterpillar Tachometers

I can,t find the specs on one except for the 3306 over the road truck engine and it lists it as 2200 RPMs full load.I doubt if a 621 would be quite that high tho.but gives you an idea.

I think if you look at a later 631 with a 3406 engine you will find some that use the electric tack / generator set up. It will work okay because it,s drivin from the fuel pump.
Later Bob

Cat used this style for awhile on industrial engines. This from a D333 engine.
Sure reminds me of the old Sun Tachometers of bygone rodding days. May be who the manufacturer is/was.

There are a couple of mechanical tachometer drive listed in my 3306 book (4N7249 and 6N1399) The first one is a drive with cable, the second looks to be just the drive.
They drive off the back of the governor where you normaly see a mechanical hour meter. Don't see a listing for the meter itself yet.

Found one more tach drive ( 4N4751 ) This one mounts between governor and mechanical hour meter.

Found one more tach drive ( 4N4751 ) This one mounts between governor and mechanical hour meter.

theres mechanical, semi mechanical thats a electric generator, and you can read off of a mag pickup on the ring gear.

It has been a while since my last post on this but I have made some progress. I seen some 140H/143H/160H blades with 3306 engines and tachs with 2400 rpm redline, I have come across two different 627Bs, (both with 3306s) one had a redline of 2200 and the other had a tach with a reset lock that redlined at 2600. I have come across 623E and 627Es with 3306s that redline at 2500. I can't quite remember there might have been a 623F with a 3306 - 2500 rpm. I have seen several 623Fs with 3406s and 2500 rpm tachs with hour meters included. How different were the 3306s made over the years. I was thinking of going with a 2500 rpm tach out of a 621E/623E/627E. Will these work when connected to a sending unit on the flywheel ring gear? Do I need to set switches on the back to work with the number of teeth on my ring gear? Do all 3306s have the same number of teeth on the ring gear?

Thanks for your answers in advance.

Scotia

Can only answer one of your questions. The 3306 comes with either 156 tooth or 130 tooth ring gears, at least within the 3N engine series.