Are digital hour meters RPM dependant?

[Rock Crawler]

I've read that the service intervals on tractors with a mechanical hour meter are based on crank shaft revolutions, and as such if you typically run at say 3/4 of rated operating RPM, an hour of real life use equals 3/4 of an hour on your meter. Are the new modernized digital meters also tied to rotational counts and able to compensate for reduced operating RPMs or are they a straight clock circuit that counts a minute as a minute no matter the RPMs?

 

[aczlan]

I've read that the service intervals on tractors with a mechanical hour meter are based on crank shaft revolutions, and as such if you typically run at say 3/4 of rated operating RPM, an hour of real life use equals 3/4 of an hour on your meter. Are the new modernized digital meters also tied to rotational counts and able to compensate for reduced operating RPMs or are they a straight clock circuit that counts a minute as a minute no matter the RPMs?

Every one that I have ever seen is a straight clock based meter, no RPM compensation in it.

Aaron Z

 

[mapper]

The dealership that I got my Massey Ferguson from said that the digital hour meter was based on RPM and not just time.

 

[Turbys_1700]

The older mechanical hour meters to my knowledge added hours based on RPM's at the PTO rated HP. Any RPM's lower than that would be reflected in lower hours. Electronic meters can be either on time only or RPM. Planes utilize Hobbs electronic meters and mechanical hour meters. The Hobbs units are based only on time. I would expect most tractor manufacturers set their electronic meters to a set RPM for an hour of run time. What that RPM is I have no idea. I would guesstimate some where close to the rated HP at the PTO.

 

[LouNY]

All of the electronic digital hour meters I have seen, mostly IH and Branson have been straight clocks, one way to find out for sure is to let the tractor idle for ten to fifteen minutes and see how much the hour meter changes, if it displays 1/10s of hours, 1/10=6 minutes

 

[Goose69]

All digital hour meters I have ever seen are straight clock, as well, RPM is not factored into them..
...I know some of the equipment I've owned, had the hour meter tied into the key switch, so the engine didn't even have to be running, to add hours.

 

[MHarryE]

Straight clock. Properly done also oil pressure switch in the circuit to make sure engine is running to count hours but my Kubota RTV-900xt is switch on, meter runs.

 

[BrokeFarmerJohn]

I clocked my meter on my JD 4320, it’s to the T just a clock, RPM makes no difference.