Hour Meter

[ryer]

Hey guys,
This might sound like a dumb question but does the hour meter on a new tractor (B26) actually mean one our of time on your watch or is the hour on a tractor meter different? For example...is 50.2 to 50.3 on the meter actually 6 minutes? You would think that it is but my meter takes longer than that. So, is my meter malfunctioning or is there a difference? Thanks.

 

[mrwitty_1]

My older B7100 hour meter works just as you stated, multiply the white digit on the left by 6 and that is the minutes into the hour, example : 4 x 6 = 24 minutes. Mine is dead on with a regular clock.

 

[HOYT.TRYCON]

My understanding of a tractor hour meter is that it shows one hour of use when the tractor runs one hour at the tractors rated rpm. Alot of Kubotas have a rating at about 2600 rpm but it does vary some from model to model. To give you a example, it would take two hours of engine running time at a high idle of 1300 rpms to put one hour on the meter for a engine rated at 2600 rpm.

 

[Treemonkey1000]

They all should be the same. That's engine running time. Each 1/10 of an hour is 6 minutes. Unless you are a Lawyer then it adds up to about 20 minutes of charging time....

 

[Jimbrown]

There are two kinds of hour meters. One type just records time exactly like a clock when the key is on. The other type commonly called a HOBBS meter records time based on engine RPM. Typically one hour would egual one hour of time at what ever RPM equates to 550 power take of rpm. If running at 225 power take off rpm that would equal 30 minutes. I do not know what type the B26 has. I suspect it just records time with the key on.

 

[KeithInSpace]

I have never personally witnessed a "PTO" hour meter, but from discussions here, I'm convinced they exist. I have no clue where the break point is where the regular-hour hour meter matters less and the PTO-hour hour meter matters more, but a general statement is that larger equipment measures the hour by PTO revolutions as stated. I am certain my BX measures an hour by time...regular hours.

It probably stems from accurate service intervals for larger equipment. If it is equipment that spends a certain amount of its life idling or puttering around off idle, it would greatly increase your service intervals (have them be further apart) to have the "hour" measured off of engine rpm's rather than by an hour's time. So if I made something of a guess, the "agrictultural", "contruction" or "working" machines...the L, the M, the TLB B series (B26, not the tractor B) would have an rpm type gauge.

Us regular folks with the smaller tractors get regular hour type stuff. It takes forever enough to get 100 hours on my machine...if it was measured by engine or PTO RPM, it would take 3 years for me to change the oil, for goodness sake.

 

[steverichmond]

Taking the question a little different direction. Does anyone know if the BX2350 hour meter increases if the Key is simply on or does it only increase when the engine is running? I had a riding lawn mower click off 40 hrs before I noticed the key was accidently left on.

Thanks,
Steve

 

[ryer]

Hey guys,
I think the mystery is solved. I called the dealer and he had no clue. So, here is what I did...I took a stop watch and I measured an interval from 68.9 to 70.0 at idle (about 900-1000 rpm). It took 13 min 40 sec. I then measured the time between 70.0 and 70.1 at about 2500 rpm (540 pto on the gauge). It took exactly 6 minutes. So the B26, which does not have the electronic dash like an L39 must have a meter that runs off of rpm. Of course, this will probably all change next time I try to measure it...or maybe my stopwatch is broken. Thanks for the input!

 

[Treemonkey1000]

Well gee I was wrong on that one. I would have expected all of them to be engine on time no matter what RPM. I will have to see what my Kubota does

 

[KeithInSpace]

Does anyone know if the BX2350 hour meter increases if the Key is simply on...

I was in a real bind for light one evening and my only choice at the time was to use my tractor's headlights. To turn them on, the key must be rolled all the way to the "run" position. As such, the hour meter was definitely rolling. Burned an hour off the 'life' of my tractor that night.

So I am 99.6% certain that the BX hour meter...at least on my BX2230...measures a true hour regardless of engine RPM. I would expect that to be true across the BX line. And given the earlier example, it makes sense. I would expect that to be the case in their ZTR's and smaller mowers as well. Not sure about the B tractors. Makes sense that the B26 is an rpm measuring type given the construction environment it was designed to operate in.

 

[xlr82v2]

"Hobbs" time is by the actual clock... it's an electric hourmeter, either powered off of the ignition switch, or an oil pressure switch.

Tach time is based off of a certain number of engine revolutions. At "rated" rpm, .1 hour is 6 minutes, 1 hour is 60 minutes. If you run the engine faster than rated speed, then 1 hour on the hourmeter will be somewhat less than 1 hour "clock" time. And, by the same token, if you are running the engine slower than rated rpm, then 1 hour tach time will be somewhat longer than 1 hour "clock" time.

Back when I was learning to fly, the Cessna 152's had both Hobbs meters, and hourmeters on the tachometer as well. We learned that if you kept the idle speed low enough during taxi, that the hobbs meter wouldn't run (the hobbs meter was powered by an oil pressure switch). So, at the beginning of taxi, you would build up as much speed as you safely could, then pull back to slow idle for as long as possible, to try to prevent the Hobbs meter from running...who wants to pay for taxi time? You paid for the airplane according to Hobbs time, but all of the maintenance on the airplanes was done according to tach time... Tach time was almost always .2 hours less than Hobbs time. Pretty good racket, huh?!

 

[yekrut]

Interesting stuff. I have an L39 and was wondering about this not to long ago. Sometimes it appeared I was on the tractor longer than the meter suggested. I wonder if the L39 is a tach meter like the B26?

 

[N80]

My tractor is definitely tach time. I can do a lot of low rpm type work and it hardly moves. This seems odd to me. I can beat the machine pretty hard, and strain the engine a lot at under 2000 rpm. So it seems to me that the hour meter does not provide a good indication of what the tractor has been doing. But, I don't guess real clock hours would either.

 

[KeithInSpace]

...does not provide a good indication of what the tractor has been doing.

I think the way to think about this is that oil doesn't break down by itself. It needs heat and friction. Each time a combustion event takes place, a little bit of the oil is fouled. Less combusion events mean less oil is fouled, no matter how hard the engine is 'pushed'. Similarly, 1,000 RPMs generates significantly less friction and heat than 3,000 RPMs, further increasing the (relative) life of the oil.

Just as similarly, running the tractor at an RPM HIGHER than the magical 540 PTO RPM would put more stress on the oil, thereby hastening the hour meter's passage of "time".

 

[xlr82v2]

My tractor is definitely tach time. I can do a lot of low rpm type work and it hardly moves. This seems odd to me. I can beat the machine pretty hard, and strain the engine a lot at under 2000 rpm. So it seems to me that the hour meter does not provide a good indication of what the tractor has been doing. But, I don't guess real clock hours would either.

Nope, tach time is just an indication of how many times the crankshaft has spun around. Hobbs time is just an indication of how long either the engine has been running, or how long the key has been turned on.

If I had to pick between the 2, I'd say that tach time is an overall better indicator of when the tractor needs to be serviced. But neither of the 2 types gives ANY indication of how hard/easy the tractor has been worked... just "hours".

 

[N80]

I guess I always thought of it in terms of the whole tractor, but really it is only about the engine.