TrippleT said:
I did not claim perfection, for an hour meter. Why do the manuals say change the oil, filters, hydraulics, etc every so many hours? I guess some common sense has to be used along with it.
TTT,
Well said. common sense has to be used.
Here's how I look at things. Others often see them differently. That's ok too.
Some equipment doesn't have a meter at all. Push mowers, cheap riding mowers, chain saws etc. The manual tells you to service them every so many hours of operation. Almost nobody uses a stop watch and times how much use they are giving them. That's ok, they are cheap and often used as a disposable item -- much to the glee of the manufacturers. That's the bottom of the heap in maintenance indicators and the least expensive to manufacture (0 cost!) - agree?
Next up is a meter that runs a clock, so that when the key is on the meter runs at a constant set rate. Then you can look at the clock and every 10, 50, 100 hours do the maintenance. That's better than nothing, but it does not distinguish any difference between using the lawn tractor to pull a small trailer with kids and hay bales around during a birthday party at 1/3 throttle, cutting an overgrown field at max throttle or using just the headlights with the engine off. (I've done all three) In fact - it doesn't even care if you left the key on for a week - the clock still racks up hours. (yup - did that too!) So, that type of meter is a step up, but still could be better - agree? Cost in volume is about $1-3.
Next up is a meter that counts engine revolutions. They are nearly universally calibrated to show one "hour" of use based on a particular RPM. Usually for tractors, that is the PTO engine speed. If the rated speed is 2600 and you are cutting a field at 2600 - it racks up hour for hour. If you are pulling a wagon with kids and hay at 1300 rpm it racks up 1/2 hour for every time hour. They used to be called "Proof Meters". My understanding is that they were proof of how much work the engine has done. That makes some sense as wear is related to friction and distance. Rub something for 1 foot it wears so much. Rub it the same way for 2 foot it wears approximately twice that much. It's more complex than that, and so this meter is a step up, but still could be better - agree? Cost in volume is $5-15
Next up is having 2 meters - clock meter and RPM based meter and you can gain some understanding of how the machine was used. If the two meters are almost the same reading -> the tractor has been worked hard. If the meters are 2x or 3x different, the tractor has idled a lot. There are different things that can go wrong with tractors operated in those two different ways. Multiple meters of different types are used in airplanes and other critical pieces of equipment. That is a step up - agree?
Next you can think about what causes wear. Friction, contamination in the air, oil, hydraulic fluid, high temperatures, low oil pressure, etc etc. Then you can add a sensors and use a computer to tell you what to do and when to do it based on real use and not on a set schedule. That's a step up again - agree?
Each step up outlined is also a step up in cost as well as a step up in quality of information to the owner / user of the equipment. Most companies that make tractors and other equipment want to economically provide data to users that is appropriate to the equipment's intended use, investment and the sophistication of the user. Most tractors are designed to be used to work at the PTO speed. Tilling, cutting, plowing, discing, haying etc. So they put on a meter with a calibration for PTO speed. That type of meter is about the minimum you would want to see.
In the future, I anticipate the computerization of maintenance meters. Engine controls are already advanced and have enough computational power. Just a few more sensors (differential pressure across the air filter, oil pressure, oil temperature, throttle position, wheel speed, wheel slip, gear used etc) and some program time. Heck, most of those sensors are already there....
jb
