Governor on the street?

First question... is it likely that my old 6BT-powered box truck used a governor instead of a normal direct link from the pedal to the pump?  Here's why I ask.  It had a PTO and a mechanical throttle handle so you could lock the RPMs where you wanted.  In its former life it was a blown-in insulation truck and the PTO drove the blower.

So when it was using PTO (or when a tow truck uses hydraulics off PTO or whatever), is the the set idle speed maintained by a governor, or is it maintained by the fact that the implement is only using a fraction of the torque being made by the engine?

Am I making sense?  I'm trying to figure out if trucks like that are a mechanical link from the pedal to the pump, or if they use a governor like a lawnmower, tractor, or generator.

Good question, i always assumed that the idle-up lever was basically a second cable gas pedal. The one I tried in a backhoe felt that way. Heavy loads on the hydraulic system would cause the revs to drop a bit.

Most industrial equipment has a hand throttle to set the rpm.   No governor that I know of.

On the Fuel Pincher powered fire truck I've driven the hand throttle is just that. It effectively just pushed the accelerator pedal for you. 

Right... but does the pedal and/or hand throttle just go straight to the "throttle," or does it go to a governor system?

For instance in a tractor, lawn mower, or generator, the RPMs are held constant under different loads by a spring loaded governor.  If you're on a tractor with a brush hog and hit a heavy patch of grass, the RPMs [at least attempt to] stay constant as the governor opens the throttle more in response to the load.

I think I'm talking about the difference in types of governors.  In something like a commercial truck, there is a governor that prevents over-revs, but the pedal is attached directly to the throttle/fueler on the pump.  Then, As you approach (let's say 2200 rpms), the governor springs reduce fueling so it won't accelerate any more.  We'll call that a "fixed" governor.  The governor in a tractor is a bit similar, but actuating the throttle lever pulls on a spring on the governor.  Most lawn mowers are the same way.  When you throttle up, its just pulling on a spring that "skews" the governor.  That way, if you throttle up to 2000 rpms on your John Deere and put it in first and let out the clutch, it will return to 2000 rpms after you engage it.  We'll call that a "variable" governor.  I think we've all played with the springs on our Briggs and Stratton push mower to rev it up, yes?

Similarly, a generator running at 3600 rpms powering a light bulb will open up the throttle to maintain 3600 when you pull the trigger on your circular saw.

I'm trying to determine if a "variable" governor like in a generator or Kubota would work on a street vehicle... particularly one that does several duties; some highway, some DD, some off-road, some towing.

In reply to Curtis :

So what youre hoping for is a governor in the street and a crooked city councilman in the sheets?

There are two types of governor or diesel throttle strategy.

Load based and RPM.

In Semi-trucks you can feel the difference when you shift. Some you don't have to lift the throttle much when shifting. (the RPM doesn't flair when you remove the load).

Which injection pump is it?

In reply to bentwrench :

So I'm assuming that the load-based is what you would find on generators, lawn mowers, and tractors?  The RPM-based is just the "rev limiter"?  Or is that backwards.

Example.... one of our tractors is a JD 750.  It is a manual and has a foot throttle in addition to the hand throttle.  I can drive it like a car (double clutch and blip the throttle to match).  The hand throttle you can see pulls on a spring which attaches to a governor lever on the pump.  When you encounter a greater load (engaging PTO, going up a hill, etc) you can watch the governor push itself forward to keep the same RPM and vary the load.

Are there trucks/vehicles/etc on the road that use that type of governor?

My real reason for asking is for a potential diesel swap.  Diesel engines with the tractor-type governor are cheaper and I have a good source for them, and a tractor-type governor would work well in many of my situations.  When off-roading, it is nearly impossible to keep your foot in the same place when you bump over rocks - causing unexpected big throttle changes.  Many off-roaders install a hand throttle for off roading to avoid that issue.  Theirs of course simply holds the pedal and throttle at a fixed point which means they still have to adjust it for hills, etc.  I was thinking if I had a tractor-type governor, I could set the hand throttle to a fixed RPM and not have to mess with it.  It would also work as cruise control on the highway.

I'm just not keen on making it a bear to drive for some reason and was hoping we could discuss it.

The way my brain logics it out, the only real difference I should expect with that type of governor on the street is that at half pedal, it would accelerate up to X rpms and then hang there, unlike a regular throttle which would slowly taper off acceleration as the load you selected with the pedal (on a graph; parabolically) begins to meet and equalize with drag, friction, torque curve, etc.

bentwrench said:

In Semi-trucks you can feel the difference when you shift. Some you don't have to lift the throttle much when shifting. (the RPM doesn't flair when you remove the load).

I have driven enough of them that I should know, but in all honesty 99% of my shifting is at redline anyway.  I would run it up to 2200 at WOT, clutch, and hold the throttle down.  It would stay at 2200... but is that because it was just hitting the redline governor, or was my foot position just limiting the revs.

I never really tried just clutching at half load to see if the RPMs flared.

Daylan C said:

Which injection pump is it?

It was a P7100 on a 5.9L 6BT.  I sold it long ago or I would post pics.

gearheadmb said:

In reply to Curtis :

So what youre hoping for is a governor in the street and a crooked city councilman in the sheets?

I.... think... so?  As long as she's hot, it sounds good.