Hour meter accuracy

[Jay4200]

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]

</font><font color="blue" class="small">( 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. )</font>

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]

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]

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

 

[Mike_Lipke]

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]

<font color="blue"> could that actually be right? </font>
Yes. Unless you have one of the smaller model <font color="orange"> Kubota's </font>. One hour is only accurate at 540 PTO speed.

 

[BB_TX]

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]

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]

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]

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.