Technical Can anyone ID this 1933 mechanical tacho/rev counter ?

Please have a go. Even if your not sure, may spark someone elses brain . Date on the backside says AUG 1933. Size is 3&5/8th inch diameter. Thats 9cm. Calibrations look hand painted. Needle moves freely if i shake it. ( like a speedo needle ) Is that OK ?

 

neat .

 

Manufactured by Stewart Warner. Original application, who knows? With the original face wiped out you may never know.

 

So does a mechanical tacho work just the same as a speedometer with a cable and thats it ?

 

would reverse rotating be a clue to anybody?

 

Yes, tachs work just like a speedo: insert cable, rev engine.

The marking on the backside is not the usual SW way of indicating a date, which is usually a single number and letter which fit a specific dating code. I've seen the code on gauges destined for aftermarket as well as production cars. So I don't know why this one actually has the month and year stamped on it.

The reverse rotation is odd, but not unique. I've seen tachs built for Cobras with reverse rotation, as well as boats. Some boats have two engines, and they would rotate in opposite directions, and each got a tach. Maybe this is from an early boat application?

 

Back when Chris Craft was using (mostly) Hercules engines they used reverse rotation tachs. They were Stewart Warner and only went to 4000 rpm. What were they building in the early 30s that needed a 5000 rpm tach?

 

Thanks for the info guys. Maybe it,s a postwar conversion for something faster.