WOT on diesel tractors

[FatSlob]

far too often I read where most tractor owners run their machines at below pto recommended speed for loader work on hydro machines. I understand the pto marker and how it is recommended because of max torque. However, I don't understand why people run there machines between 1500 and 2100 rpms for loader work. Why not run them at above pto marker and at full throttle? There is a reason why the factory allows it to run above pto marker right? That would be to take full use of the cycling rate of the hydraulics when using the loader. So what gives? If the excuse is to save life on the motor, I don't think that you really are benefitting yourself because most construction equipment is ran at full rpms such as excavators and dozers to take full use of the machine. Just curious on what some of the reasoning is. thanks

 

[yelbike]

Fuel economy? If i don't need the full power why run it at max rpm.

 

[Sysop]

You buying my fuel? ...and with an open station my Aspirin? ...along with a few years from now, my hearing aides?

I'm generally fairly close to PTO speed all the time unless just moving it around a bit for changing implements or to park it or whatever. HSTs need fluid pumping to keep them cool, so I generally keep my RPMs up kind of high any time I'm operating the tractor for a work task. Only time I run the engine over the designated PTO RPM mark is when I'm rolling along trying to get someplace in medium range and want a little more speed but stopping to go to high would be a waste of time, and on those occasions I only run it above the PTO mark long enough to get where I'm going and then back it off to PTO or slightly lower... My engine runs 2400RPM for 540PTO, so generally the lowest I'm operating at is the high end of your range; 2100RPM, perhaps dipping to 2000 under load (if they are dipping under load, I give it more juice so the loads aren't affecting it). The highest I've ran it has been 3000 of the 3400RPM red line while traveling.

I personally try to find a balance of where it gets the best performance, remains the coolest, doesn't suck fuel, doesn't blow out my hearing (I really can't imagine going full throttle through a barn cleaning it out with the FEL), and makes my seat time the best possible experience it can be...

 

[kuboman]

far too often I read where most tractor owners run their machines at below pto recommended speed for loader work on hydro machines. I understand the pto marker and how it is recommended because of max torque. However, I don't understand why people run there machines between 1500 and 2100 rpms for loader work. Why not run them at above pto marker and at full throttle? There is a reason why the factory allows it to run above pto marker right? That would be to take full use of the cycling rate of the hydraulics when using the loader. So what gives? If the excuse is to save life on the motor, I don't think that you really are benefitting yourself because most construction equipment is ran at full rpms such as excavators and dozers to take full use of the machine. Just curious on what some of the reasoning is. thanks

Do you run your car full throttle in first gear. Because there is a mark on the tach indicating pto speed does not mean you have to run it there. It is there to show the operator what rpm the pto turns a specified speed.

 

[Scooby074]

I generally run mine in the upper 1/3 RPMs. To get the most power and hydraulic flow (speed). Overly low RPMs (lugging) is hard on diesels.

There are many owners on here who baby their equipment. Its their right, but sometimes it does more harm than good.

As to hydro noise, get some of these, plus you'll gain a radio! Closest to being in a cab.

 

[ddivinia]

How much more fuel does it burn at WOT vs. half throttle?

I know that when I am running my tractor that even though it is at 540 RPM PTO the turbo is always singing. When I put it under load - it does start singing.

When DPF emissions hit the smaller tractors, I bet people start running them harder to clean the DPF.

D.

 

[TomSeller]

Do you run your car full throttle in first gear. Because there is a mark on the tach indicating pto speed does not mean you have to run it there. It is there to show the operator what rpm the pto turns a specified speed.

I'm kinda the same way, I run at the 540 marker when running a PTO device, but otherwise I run at what is comfortable for the engine. I don't lug it, but I don't waste fuel either.

 

[Redneck in training]

Running at lower speed doesn't necessarily save fuel. Fuel consumption is more or less proportional to load. In fact looking at the engine charts it is usually the PTO speed where the specific fuel consumption [g/kW/Hour] is the lowest. I run my engine at lower than PTO speed to limit noise but rarely at less than 2000 rpm.

Kubota Engine America - Kubota Engine Line Up - Before 2013 here is a Kubota 2013 engine line up.
http://www.kubotaengine.com/assets/documents/15_v1505t_30.pdf here is 1505 turbo
http://www.kubotaengine.com/assets/documents/13_v1505_30.pdf here is 1505 naturally aspirated

Look at the bottom of the chart where the fuel consumption curve is. Naturally aspirated engine has the best fuel consumption at about 2200 rpm while the turbo at about 2000 rpm.
The turbo has about 4% better fuel consumption. Another advantage of the turbos is they are quieter because the turbo removes large portion of exhaust gas energy. In other words the velocity of the exhaust gas downstream of the turbo is much lower than in naturally aspirated engine. That means less exhaust noise.
Turbo is way to go.

 

[RedNeckRacin]

WOT on some machines makes the hydraulics jerky if your not a skilled operator at that particular piece of equipment as well. It even makes good operators look bad too. For my hydro machine i run it right around the PTO marker for the cooling of the trans. MY gear driven deere, gets run at whatever works. If I know I am going to be doing heavy loader work, I usually set the RPM's at around 1500-1800 to prevent stalling and use the foot throttle to bump it up when i hit the pile or need more hydraulic flow for dumping.

 

[FatSlob]

Do you run your car full throttle in first gear. Because there is a mark on the tach indicating pto speed does not mean you have to run it there. It is there to show the operator what rpm the pto turns a specified speed.

Yes I do run my car at full throttle when I have the loader attached to it so I get max cycling rates when I'm tryin to get a truck loaded faster. I know what everything means on the machine. Was asking a question on others reasoning. No need for anyone to get funny. So the census seems to be to save fuel. Fair enough

 

[Scooby074]

Yes I do run my car at full throttle when I have the loader attached to it so I get max cycling rates when I'm tryin to get a truck loaded faster. I know what everything means on the machine. Was asking a question on others reasoning. No need for anyone to get funny. So the census seems to be to save fuel. Fair enough

Fuel may be a part of it, but I think to many users on here the noise weighs in. Frankly I think some are "scared" of the noise their tractor makes at full throttle. Not just the volume for their hearing, but they think "that doesnt sound right, and must be putting way more wear on the engine!!!" and throttle down as a result.

 

[ddivinia]

If I am doing a bunch of loading I will run lower than full and use the foot throttle when I need more hydraulic pressure.

D.

 

[Tx Jim]

I agree on running lower rpm's while loading/unloading hay while utilizing foot throttle to spped engiine up when required. Anyone that thinks lower rpm's isn't saving fuel is only fooling themselves.

 

[PapaPerk]

Because good operators know when to use full power and when not too.... That's why tractors are equipped with throttles.

 

[Sysop]

Because good operators know when to use full power and when not too.... That's why tractors are equipped with throttles.

+1 :thumbsup:

 

[TripleR]

Because good operators know when to use full power and when not too.... That's why tractors are equipped with throttles.

+2 :thumbsup:

I grew up using tractor on which the tach often didn't even work.

 

[JDTank]

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.

 

[arlen4720]

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

That is a load of ****. I think what you are saying is that hydrostatic transmissions require sufficient "charge" pressure and flow to operate properly. That sures the **** ain't full throttle.
Run the RPM's up to the point the tranny is not "sqawling" and you have enough charge pressure.

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.

The gear pumps don't care about the RPM, they just move so much oil per rev. What isn't used bypasses back to tank. More RPM's are more wear not less.

Don't get me wrong...there is nothing "wrong" with runnig at full throttle, I'm just saying use the amount of power and RPM's you need for the job at hand.

 

[rider0]

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?.

So manufacturers install throttle levers and linkages for the sole purpose of evoking nostalgia?

 

[GManBart]

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? If you make a statement like this, you probably shouldn't own a tractor.

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.

Wow, there are so many inaccurate statements in this, that it's hard to cover all of them.

First off, not all HST transmissions are designed the same, and not all tractors are designed the same. My LS manual very specifically says to run the engine at 1500rpm+ when putting the engine under load...if it needed to be at PTO speed, or max speed to keep the transmission cool enough, or prevent other wear, they would say so.

Running a hydraulic pump at max RPM doesn't make it easier for the pump to do its job, it simply makes the pump put out more volume. Up to a certain point, the added volume causes higher pressures, but that's usually a fairly low RPM....after that, it's just bypassed. Higher RPMs cause more wear to some parts (bearings, etc), and higher pressure causes more wear to other parts (seals, valves, etc), so the pump won't last longer run at max RPM.

Running at maximum RPM will cause a higher rate of wear on things like the bearings, pistons, rings, valves, etc, etc, etc. Usually just a slight decrease in RPM will cause a significant increase in longevity. People that suggest always running at WOT because "they're designed for it" simply don't know how engines work...

I rarely run at WOT, but I do when the situation calls for it. I know it can run at WOT for a long time, but making it do so for no reason is silly.