WOT on diesel tractors

[k0ua]

Was this tread specifically posted to throw bad information on the web? If anyone truly believes that running a tractor a WOT all the time is good, than do so, just don't borrow or use anyone else tractor. For the rest of us not insane folks, we will continue our "abusive" tractor practices!

Amen. End of Story.

 

[jenkinsph]

Problem with some threads is a complete lack of common sense. takes the fun, enjoyment and chance to learn something out of the loop. Some days I can learn something new on TBN, other days not so much.

 

[SPYDERLK]

For tractors with hydrostatic transmission, the pumps are designed VERY SPECIFICALLY to run at their rated RPM input speed, which is full throttle.

I don't know how many times I have to type this out on these forums. Hydro pumps on smaller machines have multiple pistons inside of them. If you work your tractor at less than full RPM, the load of pressurizing the oil is not distributed equally across all of the pistons inside the pump. This creates excessive heat and is hard on the seals on the pistons, since the load is not distributed across all pistons equally. This isn't rocket science. Hydrostatic tractors are designed to be run at full RPM. If your just moving the machine, or driving around, 3/4 throttle is ok. If your doing any kind of work, and you aren't running at full throttle, you shouldn't own a tractor. Why buy something to use it the wrong way?

Tractors with gear transmissions and a controllable throttle are a different story, to some degree. While the drive-train is not controlled with hydro fluid, your hydraulic pump powering your loader, power steering, 3 pt arms, all of that stuff, is still suffering the same fate. The higher the RPM, the easier it is for your pump(s) to do their job. In turn, they will last longer.

Fuel economy in a diesel engine is more dependent on load, than RPMs. I wouldn't let that be a determining factor in your choice to run at certain RPM's. Why spend a minimum of $10,000 to get into a diesel tractor, and than gripe about buying $40 worth of fuel? You think your saving money on fuel, if you are, it is pennies worth, but you forget you are decreasing your hydro pump life. In the end, that will cost you money too.

The old myth about diesel engines running at high RPM's being bad for them is long gone. People forget that engines today, especially diesels, are built to tolerance levels greater than ever before. Machining is extremely refined, oil lubricating qualities have never been higher. Even the small Yanmar engines like the one in my X740, running at 3,600 RPM, can easily handle it. That actually isn't a high RPM at all. I have seen diesel engines go much higher, and last just as long as low RPM diesels. With the small displacements we are dealing with, you will see high RPM's. Get into larger displacements, max RPM's drop. Large locomotive engines reach full RPM at about 950 RPM, that's it. However, they are also 16 cylinder engines, with each cylinder having a displacement bigger than that of an entire diesel engine in an HD pickup truck.

It doesn't mean a **** thing when it comes to refuting some dumb *** trying to say that you need to run your tractor at WOT all the time.

Post 17

Was this tread specifically posted to throw bad information on the web? If anyone truly believes that running a tractor a WOT all the time is good, than do so, just don't borrow or use anyone else tractor. For the rest of us not insane folks, we will continue our "abusive" tractor practices!

His position is extreme, but basically true. ... And he introduced some balance in his statements. With that, I dont see any cause to argue with it. It is essentially how I run my hydrostats -- 75%+ according to severity and duty cycle of load.

On my gear tractors I will run much less esp when cool, but to get good loader response stirring the manure pile when hot - or other continuous hyd work - I run about 80%. Id run full, but all the hi rpm clutching just accentuates clutch wear. The hyd system wont even reach relief pressure hot at lo idle [~25%]. Thats internal pump leakage.
larry

 

[arlen4720]

His position is extreme, but basically true. ... And he introduced some balance in his statements. With that, I dont see any cause to argue with it. It is essentially how I run my hydrostats -- 75%+ according to severity and duty cycle of load.

On my gear tractors I will run much less esp when cool, but to get good loader response stirring the manure pile when hot - or other continuous hyd work - I run about 80%. Id run full, but all the hi rpm clutching just accentuates clutch wear. The hyd system wont even reach relief pressure hot at lo idle [~25%]. Thats internal pump leakage.
larry

So, you're saying to run the engine RPMs to match the conditions for the job at hand? Well then I think everybody is in agreement.

 

[jenkinsph]

If your pumps have lots of wear you may have to run the higher rpms' to get good response. I can hit relief at idle on my fel regardless of how long or how hot the day is. Most of my fel work whether pushing into a pile or simple blading is performed between 1500 and 1800 rpm, if I run faster than that the fel simply moves too fast. Pops the front wheel up in the air and so forth, puts undue stress on the fel and tractor in general. I am not new to fels or backhoes either and my tractor (110tlb) performs like new still after 8 years of use.

Something not mentioned so far is that it is a very good idea to watch the temperature guages for the engine and transmission closely. If the temperature rises too high you may wan't to rethink how you are working your tractor.

 

[PapaPerk]

Gotta love the guys that "Set It and Forget It". It's a tractor not a turkey cooker! Use some common sense.

 

[RDrancher]

My tractor accounts for about 70 percent of my income. I'm supporting a family of eight at the present time, including inlaws...FWIW. My tractor has never seen full throttle. Same goes for the mini-excavator and CTL for that matter...unless the CTL is running a mulcher, which needs the hyd flow.

If you need to run your tractor at WOT, you need a bigger tractor!

 

[TomSeller]

If you need to run your tractor at WOT, you need a bigger tractor!

About time someone said that. I don't know what "Full RPM" WOT is on any of my machines because I never rev them past 540 RPM. I am guessing "3/4 throttle" is about 540 RPM on most. I can't imagine using 3/4 throttle moving the tractor as was suggested.

To get from one end of my property to the other I might go through 20 gates. If I figure 2 min per gate, getting off, opening the gate, moving forward, getting off, closing the gate, checking for phone messages, pulling a weed, pushing the cows back, etc, that is 40 minutes at the gates. I idle it while I do this, 3/4 throttle would be excessive use of fuel to me.

 

[jenkinsph]

Tom,
Sounds like you live in a gated community for sure.

 

[Gary Fowler]

About time someone said that. I don't know what "Full RPM" WOT is on any of my machines because I never rev them past 540 RPM. I am guessing "3/4 throttle" is about 540 RPM on most. I can't imagine using 3/4 throttle moving the tractor as was suggested.

To get from one end of my property to the other I might go through 20 gates. If I figure 2 min per gate, getting off, opening the gate, moving forward, getting off, closing the gate, checking for phone messages, pulling a weed, pushing the cows back, etc, that is 40 minutes at the gates. I idle it while I do this, 3/4 throttle would be excessive use of fuel to me.

You must be related to my BIL. He has at least 14 gates on his 30 acres of pasture.