Hour meter accuracy

Jay4200 · Dec 13, 2005

Sorry for all of the recent posts, but I'm trying to learn as much as I can about all of these newfangled tractor thingies...

I read a post from a few years ago - the poster said that the hour meter on his Kubota (B-series, I think) was only accurate with the motor running at PTO speed, and would read lower as RPMs dropped - meaning that the meter is actually an [Hour*RPM/PTOrpm] meter. I find that shocking - could that actually be right? How accurate is your meter?

Thanks - Jay

DK35vince · Dec 13, 2005

( I read a post from a few years ago - the poster said that the hour meter on his Kubota (B-series, I think) was only accurate with the motor running at PTO speed, and would read lower as RPMs dropped - meaning that the meter is actually an [Hour*RPM/PTOrpm] meter. )

Both of my tractors are set up the same way.
Engine hours are based on engine speed (RPM's). The motor needs to run at a certain speed to show 1 hour on the clock, the slower the engine speed the slower the hour meter runs.

Iplayfarmer · Dec 14, 2005

It's the same way in other engines too. For instance, the engine oil life monitors in my vehicles account for engine rpm, temp, etc. It's a little better than just mileage, since miles differ in their impact on engines, oil life, etc.

In my opinion the hour meter being linked to rpm's is a better way to track wear on the engine. A tractor sitting at idle for an hour is going to acquire a lot less wear than an engine running at PTO speeds mowing for an hour.

I guess it's a little confusing that it's called an "hour" meter when it's actually a "rotation meter" that tracks the number of rotations.

midlf · Dec 14, 2005

The hour meter on my BX2230 is electric and has no relation to engine speed.

Mike_Lipke · Dec 14, 2005

Both my Kubota BX and my Cub Cadet are hooked up to the 12 volt supplied by the key, and run the same speed all the time. Even with the engine off, but the key on all night, they tally up the number of hours that they get voltage. It might be a good idea to tie them into engine speed, but mine, at least, don't do that.

ronjhall · Dec 14, 2005

could that actually be right? 
Yes. Unless you have one of the smaller model Kubota's . One hour is only accurate at 540 PTO speed.

BB_TX · Dec 14, 2005

Many are mechanical and have a speedometer type cable from the engine to the meter. The faster the engine runs the faster the meter turns. It is calibrated to give 1 hr at rated PTO speed. The meter works the same as an odometer on a car except the odometer works off the final drive line so the faster you drive, the faster it turns, but is calibrated to give miles driven.

ccsial · Dec 14, 2005

Tachometers with hour meters are also used on aircraft engines. Most planes have an electric hour meter and tach hour meter. One is "airframe hours" the other is referred to a "tach hours" and is proprtional to the number of revolutions the engine has made.

It makes sense on a tractor to have tach hours. I guess small tractors with electric meters comes close to tach hours since most small tractors are supposed to spend much of their life at PTO speed (usually full throttle). If you don't install a tach the electric meter is a cheap alternative.

As far as accuracy it is not a big deal. The meters are used for maintenance intervals and determining how much use is on a tractor. Even then, the tach hours don't tell you hard hard of duty those hours were accumulated at.

3RRL · Dec 14, 2005

Very interesting. I never paid attention to that.
Does anyone know what it is on the KAMA? ...electric or mechanical...??

Mechanical sounds like it better reflects engine wear.
Thanks,

Bird · Dec 14, 2005

The thing I don't understand is how the tractor manufacturers decide which kind of "tach" to use. My '95 B7100 had the electric clock; i.e., ran the same speed with no relation to engine rpm anytime the key was turned on, while my '99 B2710 had the engine rpm tach. Ideally, I guess you'd have both on tractors just as some airplanes do. And of course some other vehicles use a dual system, also. When my brother was a Matco Tool distributor, his truck had the normal odometer and an engine hourmeter, but those trucks (same with Snap-on, MAC, etc.) are mobile showrooms. They travel relatively few miles, but the engine, lights, air-conditioning, etc. are never shut off all day so the service intervals were determined by the engine hourmeter instead of the odometer.

ccsial · Dec 14, 2005

Bird, Did your B7100 have a tach?

I thought that all tachs had hour meters and the electric meters were used if no tach was present. I'm sure there are exceptions to this. The decision to use a tach instead of an electric hour meter is both financial and the amount of panel space available. Electric hour meters are very cheap and don't require a cable drive. Diesels don't have electric pulses available for an electric tach.

On the computer controlled diesels the tach may be electrical so the hour meter might be real hours instead of tach hours.

Soundguy · Dec 14, 2005

( I find that shocking - could that actually be right? How accurate is your meter?
)

Not sure why you find that shocking.. Most of the 'oldies' used a mechanical 'proof' meter to count rpm and hours run. it was , and is still, common to count hours "AT" pto rpm.

A straight on/off electric hour meter doesn't do you much good. If you had 2 tractors.. and ran one at full pto rpm all day on a generator under load. and another at mid rpm just pulling a trailer.. both 'straight' meters would show same hours.. even thought the 'genny' tractor worked harder.. and that's what you are trying to gauge.. work hours.

Now.. if you 'rent' equipment.. I fully expect them to be electric on/off meters.. that way you are paying for ALL on-time of the equipment.

Soundguy

Bird · Dec 14, 2005

( Did your B7100 have a tach )

Nope, just the one "meter" that ran when the key was on and didn't run when the key was off. You know, it also had no fuel solenoid, so turning the key off only turned off the electrical system. You pulled the throttle all the way back, past a little detent, to shut off the fuel and kill the engine whether the key was on or off. So if you had left the key turned on (which I understand some have done, but I was lucky enough to not do) you'd be racking up hours on the meter while the tractor was not being used. On the other hand, with the engine running, you could turn the key off and continue using the tractor without the hour meter registering anything.

Iplayfarmer · Dec 14, 2005

"...you could turn the key off and continue using the tractor without the hour meter registering anything." 

Now there's another reason for me to prefer a tach hour meter vs. an on/off meter.

The only real info I've gotten so far in favor of an on/off electrical hour meter is from Soundguy when he was talking about the rental companies. Even then, I still think the tach meter would be better. All the rental companies I know of rent equipment by the hour based on when you pick it up and when you bring it back, not by what's on the meter. Even so, I would still think that a tach meter would be a better guage of the use and wear, etc. on the equipment.

Of course, I hardly ever rent equipment, and when I do, it's only for short periods of time.

ccsial · Dec 14, 2005

My 1910 has no fuel solenoid either. There is no seat switch either since there is no way to stop it. Throttle back to stop. My red oil light comes on after it stops so I always look for that to make sure the key is off before I close the garage.

Bird · Dec 14, 2005

( All the rental companies I know of rent equipment by the hour based on when you pick it up and when you bring it back, not by what's on the meter. )

That may be the case, in many instances, but not all. I know a couple of times my brother rented a dozer, they delivered it on a Friday evening and picked it up Monday evening. If he had put no more than 8 hours on the meter, he would only have had to pay for one day even though he had it for 3 days. But since he did put more hours on it, they charged for more than one day. Of course he knew in advance how that worked. And even though he actually used it on 4 different days (Friday evening, Saturday, Sunday, and Monday), he did put a little less than 16 hours on it and only had to pay for 2 days.

slowrev · Dec 14, 2005

some of the older tractors referred to the hour meter in the middle of the tach as a "Proof Meter". Not sure what that means, but that is what my ols IH manual calls the hour meter on my tractor. which also has what I call a hobbs type of digital hour meter as well. the digital meter appears to have quit many years ago, but the proof meter is still going. I am going to replace the digital meter with a voltmeter this winter as I refurbish the beast.

Ben

Soundguy · Dec 14, 2005

( If he had put no more than 8 hours on the meter, he would only have had to pay for one day even )

Hey Bird.. some of the rental co.'s here in Fl are the same. the GC i work for frequently rents equipment over a weekend.. and we generally only get charged 'hourly' use, depending on what it is.

Soundguy

chrisjbell · Dec 15, 2005

My '95 B7100 had the electric clock; i.e., ran the same speed with no relation to engine rpm anytime the key was turned on, while my '99 B2710 had the engine rpm tach. 

Boy that is interesting... I have a B7300 ('97 model) and it has a mechanical hour meter (at least I'm pretty sure it does - it acts like one). When I'm mowing and running at 540 all the time I can use the hour meter as a clock but when I'm digging or something where I run at lower RPMs it is "slow" and I get in trouble for being late if I use it to tell time. /forums/images/graemlins/smile.gif

jimmysisson · Dec 15, 2005

My 2120 (1993 model) has a proof meter that the manual says racks up one hour at engine speed of 1867 rpm. The rpms at PTO 540 are about 2300. It says "Use the Proof-Meter as a guide to determine hourly service and maintenance intervals." Makes sense to me.
Jim