FPM Tach drive ratio??

[whirly]

Does anyone know what the Tack drive's ratio is to the actual engine speed?

Can I assume that all of the Majors (52/60/11) up to the Minimec FSM's were the same?

[Timeee]

Good Day

I don't know the ratio, only that it is driven by a gear off the auxillary shaft. The auxillary shaft obviously revolves at half engine speed. I think the oil pump drive comes off the same gear. Presumably need to count the driving teeth on the Aux Shaft and the driven teeth on the Tachometer Gear Assembly to get an accurate ratio with engine speed.

In answer to your second question, I would think it unwise to assume all tachometer drives are the same. My Fordson Major Parts List lists three Gear (Tachometer) Assemblies: One for engines from 1954 to Feb 1956 (obviously not yours), a second "from Feb 56" and a third "from Feb 1956 to Mar 1960". I am sure others will put me right if I have got it totally wrong, but I think the last two covering your Power Major are to cope for any differences between the 2 types of tachometer fitted, one manufactured by AC, the other by Smiths.

Yours Ever
Tim

[whirly]

Timeee - Thank you for waking me up

The angle tach drive gear has 9 teeth mating to the Aux Drive gear. If I am correct the Aux Drive gear that interfaces with the tach drive gear has 18 teeth. The Tach Drive itself is 1:1 from its drive gear to the cable out. That would give the final output on the tach cable end a 1:1 for engine speed.

Please let me know if I'm wrong.

[Dandy Dave]

I have an AC drive in the basement that is off of my Power Major and apart because it was boroken. I thought I may have been able to machine a few new parts. I'll see if I can find it and count the teeth.

Would the Petrol New Major have a different drive also? Dandy Dave!