hour meter and tachometer

realolman · Sep 4, 2012

is the hourmeter on a 300 u driven by the tach? If so, do the hours accumulate faster at higher rpms?

FC Andy · Sep 4, 2012

The hourmeter and tachometer are cable driven from a location on the distributer. The hours accumulate accuratley at most likely 1650 rpm. It should say Engine hours at __ RPM right on the face of the tach. (A 450, for instance, is at 1450 RPM.) -Andy

David G · Sep 4, 2012

Hours on a mechanical tach will accumulate hour for hour at
rated RPM and proportional as RPMs decrease. An electronic
tach is hours run, regardless of RPM.

FC Andy · Sep 4, 2012

I looked at new ones on EBAY really quick, looks like engine hours are at 1750 RPM. -Andy

realolman · Sep 5, 2012

(quoted from post at 17:29:15 09/04/12) I looked at new ones on EBAY really quick, looks like engine hours are at 1750 RPM. -Andy

You know I have looked at those tachs how many times and I never noticed that. Actually I think its 1450, but that's beside the point...

Thanks for pointing that out.

mkirsch · Sep 5, 2012

That's why they're called "Engine Hours."

I believe you'll see that tractors with electrical hour meters are marked "Operating Hours."

realolman · Sep 6, 2012

(quoted from post at 05:10:37 09/05/12) That's why they're called "Engine Hours."

I believe you'll see that tractors with electrical hour meters are marked "Operating Hours."

Seems to me the mechanical one could be more accurately associated with the actual number of engine revolutions, rather than time

How does the tach use the cable revolutions to move the needle up to a certain point and then stay there, rather than keep spinning? Is there some sort of "governor" mechanism in there?

Jim Becker · Sep 6, 2012

(quoted from post at 06:18:46 09/06/12)

(quoted from post at 05:10:37 09/05/12) That's why they're called "Engine Hours."

I believe you'll see that tractors with electrical hour meters are marked "Operating Hours."

Click to expand...

Seems to me the mechanical one could be more accurately associated with the actual number of engine revolutions, rather than time

How does the tach use the cable revolutions to move the needle up to a certain point and then stay there, rather than keep spinning? Is there some sort of "governor" mechanism in there?

The hours reading is literally a revolution counter. Take the reading, multiply by the "at RPM" number, multiply that by 60 minutes per hour and you will have the engine revolutions that the meter has clocked.

A mechanical tachometer is exactly the same as a mechanical speedometer. The input shaft is coupled to the needle through a magnetic coupler, where speed is translated to a force. Here is a page that shows the insides of a speedometer. The bike speedo is somewhat different from most, in that the magnetic coupler is at an angle. Most tachs and speedos have the cable straight in line with the pivot axis of the needle.
http://xjbikes.com/Forums/viewtopic/p=202812.html

hour meter and tachometer

realolman

Member

FC Andy

Member

David G

Well-known Member

FC Andy

Member

realolman

Member

mkirsch

Well-known Member

realolman

Member

Jim Becker

Well-known Member

Similar threads