Why is the hour meter on my Jubilee based on?

Why is the hour meter on my Jubilee based on engine speed? (I think) 1550 engine rpms which produced 540 pto speed would record one hour on meter in one hour of time.

Farmall governor is maxed 1550 rpm, 540 pto.

Jubilee can go faster than 1550.

What was Henry Ford thinking?? An hour based on engine speed??

Lots of old hour meters read at a certain rpm

Everybody did it. The hour meter part of a mechanical tach is only going to be accurate at one speed.

(quoted from post at 16:31:06 11/27/21) Why is the hour meter on my Jubilee based on engine speed? (I think) 1550 engine rpms which produced 540 pto speed would record one hour on meter in one hour of time.

Farmall governor is maxed 1550 rpm, 540 pto.

Jubilee can go faster than 1550.

What was Henry Ford thinking?? An hour based on engine speed??

Click to expand...

Most, if not ALL mechanical hour meters were like that, they basically counted engine RPM's and "divided" them by revolutions per hour at rated speed, displaying the result as "hours".

I know many did it. Were all hour meters based on a standard RPM like 1550? Why not use max RMS???

Hours is a misnomer, it's actually a scaled engine revolution counter. Every hour counted on the proofmeter represents 1515 revolutions per minute X 60 minutes per hour which is 90,900 revolutions for every hour shown on the proofmeter. The proofmeter collects hours slower at low RPMs and faster at higher RPMs so they aren't real-time hours (unless you **always** ran your engine at 1515 RPMs).

Those tach hour meters are simply revolution counter calibrated to accumulate 1 hour at a certain RPM - typically for engine RPM that provides 540 RPM at the PTO.

Back when mechanical tachs were the norm, the tach odometer on many diesel trucks, power units, etc were often labeled CRANK REVOLUTIONS X 100,000 rather than hours. Considering 100,000 revolutions works out to 1 hour at 1,667 RPM this provides a reasonable alternative to actual time hours.

No. Everybody was different. Some used rated engine speed. Some used PTO speed.

Henry never built a tractor with a tach on it.

What's the gizmo on my Jubilee that measure RPMS and hours call? Some kind of meter.
I want to think its something like poof or proof meter.

What a did they pick X RPMS instead of Y?
Or why not max RPMS?

So does a mechanical hour meter that shows RPM hours more accurately indicate engine and transmission wear based on hours? When the engine is run at part throttle putzing around the yard the hours stack up slower but there is less engine wear at a light load.

An electric tac counts hours no matter how fast or slow the engine runs. My 1086 is bumping 18,000 hours on an electric tac. Seems like a lot of hours but probably only half of those hours are hard working in the field hours. The other half was spent pulling wagons, hauling manure and loader work, all jobs that dont cause a lot of wear. But when guys see the 18,000 hours their jaws drop.

A neighbor of mine rented out his tractor a wheat harvesting crew for their grain cart. It had an electric tac. All summer long that tractor ran all day whether it was needed or not because the cart operator liked to climb into a cool air conditioned cab after she was away from the tractor for awhile. I cant really blame the cart operator because a closed cab in 100 degree plus temps can get mighty hot in a short amount of time if the engine is shut off but those hours were racking up.

The rental rate on the tractor was based on tac hours and at the end of the summer the tac showed an enormous amount of hours because of the idle time. There was hard feelings between the owner and renter when it came time to pay the rental bill. If that tractor would have had a mechanical tac the final hours at the end of the summer would have been much lower.

Call it whatever youre comfortable with. Ford always called them proof meters, but the rest of the world called them tachometers. Matter of personal preference, I guess

(quoted from post at 19:42:29 11/27/21) I know many did it. Were all hour meters based on a standard RPM like 1550? Why not use max RMS???

Click to expand...

hey were not. all I have ever seen were based on what ever engine rpm corresponded to 540 pto rpm, different from tractor to tractor. Proofmeters were a direct adaptation of the veederoot counter/speedometer/odometer from cars.

I think Henry Ford passed away April 7, 1947, before the Jubilee design was started.

Thanks Jessie.
What's with 540 pto rpm?
My RM660 woods mower says don't go over 540.
I've used the mower on Jubilee and went way past 540.
Sharp blades sound like a knife cutting cabbage.
Didn't damage the mower.
Now RM660 in on Kubota.

I like 2000 rpms on Kubota, go peddle to the floor,
5 mph is a good ground speed, mower works fine at 500 rpms.

What makes 540 the standard??

540 pto is max rpm on Farmall C.

Doesn't the 2N,9n and 8n's have same meter??

Here's an archived YT discussion that attempts to answer your question:
Why 540 PTO RPM?

(quoted from post at 10:37:06 11/28/21) Doesn't the 2N,9n and 8n's have same meter??

Click to expand...

9N's & 2N's did not have proofmeters. The 8N started without, but was added around mid 1950.

NAA uses a different gear ratio in the proofmeter.

(quoted from post at 11:16:06 11/28/21) Here's an archived YT discussion that attempts to answer your question:
Why 540 PTO RPM?

Click to expand...

....and not let us forget the 1,000 rpm PTO and different splines!