Possible to over-rev my diesel tractor?

   / Possible to over-rev my diesel tractor? #12  
But they are an option you must specify when you buy the truck. Personally, I wouldn't drive a truck that doesn't have a Jakeョ.
I have driven a few that didn't have an engine brake and they sucked.
 
   / Possible to over-rev my diesel tractor?
  • Thread Starter
#13  
High range is designed to be a higher speed road gear. I wouldn't think you're doing the transmission any favors plowing in high gear.

It's only light FEL work on level ground, but that's probably a valid point.
 
   / Possible to over-rev my diesel tractor? #15  
Does a governor prevent a run away diesel from happening ? I had a tractor many years ago that had an emergency shut off for just that reason , I believe all it did was cut off the air supply if I remember correctly . All of our diesel fire trucks use to come with them also , not sure if they still do or not as I am retired now .
 
   / Possible to over-rev my diesel tractor? #16  
Does a governor prevent a run away diesel from happening ? I had a tractor many years ago that had an emergency shut off for just that reason , I believe all it did was cut off the air supply if I remember correctly . All of our diesel fire trucks use to come with them also , not sure if they still do or not as I am retired now .

A runaway occurs with a defective governor or when the engine is getting fuel from somewhere else, such as engine oil. The only way to stop a diesel is cutting the fuel or the air. If its running on some fuel source like an engine oil leak, stopping the diesel fuel doesn't help. It will keep reving up until it blows.
 
   / Possible to over-rev my diesel tractor? #17  
I made a mistake in thinking this model tractor has 3 ranges, H, M, L, BUT the OP corrected me; It only has High and Low range.:duh:
I apologize for my error in the original, unedited post below.
It would seem you could use High range, for tasks like plowing on level grade, however I think it would be more effective to move larger/deeper snow accumulations in Low range. Note on HST tractors it is referred to as ranges instead of gears because the transmission is more of a fluid flow component than a particular selected gear in a manual transmission. The forward or reverse pedal is akin to working the clutch when looking for more or less traction in a particular range/gear respectively.


High gear is NOT for plowing or doing any appreciable work with your tractor. You should use low or medium only, and 4wd for plowing, regardless of level grade. H is for over road travel, medium and low for actual work. 4wd for traction, snow, sand, mud, etc. Differential lock, if equipped, for additional traction, when stuck or nearly stuck, in straight front to back movement, not when turning.
That's the facts, Jack.:thumbsup:*

Refer to red text above.*
 
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   / Possible to over-rev my diesel tractor? #18  
Actually, what a jake brake does is open the exhaust valve early so the compressed gas in the cylinder is released instead of forcing the piston back down, like it ordinarily does on the power stroke. That way you get the engine braking from the compression stroke without the recovery of the power stroke. I'm really not sure that compression braking is any different with diesels and gas engines. Heavy diesel trucks just have more need of powerful braking. I think a jake brake would have similar effects on gas engine.

Releasing compression would not create engine braking, it would simply reduce power output. Limiting exhaust flow provides engine braking. See what Cummins and Jacobs have to say:

https://quickserve.cummins.com/info/qsol/products/newparts/jacobs_md_nondodge.html

Jacobs Vehicle Systems | Exhaust Brakes

The wikipedia version is packed with incorrect information, including the claim that diesels without an engine brake have less natural engine braking than gas engines. This is patently false because a diesel's higher compression ratio naturally decelerates faster due to the higher energy demands of compressing an equal air volume into less space as compared to a spark ignition engine with equal displacement.

Compression release engine brake - Wikipedia, the free encyclopedia

Once again, an 'encyclopedia' that can be edited without qualification gets it wrong. Garbage in, garbage out.
 
   / Possible to over-rev my diesel tractor? #19  
I didn't intend to start an argument here, and I don't like to defend Wikipedia, but Jacobs makes two different engine braking systems. The original version (which is still used) actuates the exhaust valve early and releases the compressed air before it can push the piston back down. The second version is the butterfly valve in the exhaust manifold which can restrict the exhaust flow. This is what you will find on diesel pickups and other engines that don't have the configuration to use the exhaust valve approach. I don't know which is more effective, but it seems the valve system would work better. It also creates the very loud exhaust noise. Here is Jacobs own explanation:

Jacobs Vehicle Systems | Pioneer in Engine Braking Technology

This design has been designated a "Landmark" by the American Society of Mechanical Engineers (of which I am a proud member) as noted here:

https://www.asme.org/about-asme/who-we-are/engineering-history/landmarks/108-jacobs-engine-brake-retarder

In theory gas engines have more engine braking than a diesel without an engine brake. The throttle restriction will cause higher negative pressure in the intake manifold which will limit the mass of air being compressed and make the engine work harder on the intake stroke. The compression ratio isn't really a factor in engine braking because whatever energy you absorb in the compression stroke is almost all recovered in the power stroke (absent a compression relief system) less the slight heat loss during the cycle. However, I'm not sure that the difference between gas and diesel engine inherent compression braking is all that big.
 
   / Possible to over-rev my diesel tractor? #20  
I can confirm that a diesel without a Jake has basically zero engine braking effect. On our IH you had better respect the grade because it WILL run away from you...
 
 
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