WOT on diesel tractors

[JD6400NZ]

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

 

[Edward. S]

I also found that to be the most interesting thing in the whole thread. I hope he posts some pictures.

Indeed, pictures rock.

He found it! :laughing::laughing::laughing:

 

[Scooby074]

You have a loader on your car? Cool!:thumbsup:

Well, it WOULD make navigating traffic jams easier!

 

[arlen4720]

He found it! :laughing::laughing::laughing:

That's better than a Toocat:thumbsup:

 

[homedad]

I have an 88 yo neighbor who was a heavy equipment mechanic for a highway crew until age 74. He always said that the guys who ran at high rpm's broke much more equipment than the slower guys. He always thought that they would never do it that fast if it was their own equipment.

 

[Gary Fowler]

My B 26TLB with hydrostatic drive rarely runs more than 2000 RPM when in operation. I find this the most comfortable range both in sound and operation for hydraulic pressures. PTO speed is reached at WOT for this tractor but noise level is way high when getting above 2000-2200 rpm but since I have never used it for PTO implements, that isn't a problem. I don't find that speed of operation increases much if any by adding 400-500 more RPM either so why do it. WOT for me is used only for transport on smooth surfaces, I vary my transport speed using the throttle just like I would with a gear drive. I keep the go pedal to the floor and reach my travel speed depending on how rough the terrain is by increasing throttle. Why rev the throttle to max then run the HST pedal at half mast- just a total waste of fuel, increase in noise level and wear on the engine. IF I need to climb a hill, I just back off the HST pedal and it climbs right on up without stalling the engine. I understand that some mfg. recommendations are minimum of 1500 rpm or more, but why would you rev the engine to max to move the tractor or FEL just a bit. I get very nervous with my BIL when helping him to hook up something and I want him to back up 2 inches or raise the lift 1 inch and he revs the engine to 2000 rpm to move it.
Whenever I first crank my B26TLB to back it out of the shed, it stays just above idle which is 1200 RPM (a bit high) till I get it out, turned around etc., only then do I increase RPM. If moves itself on flat ground and raises the FEL just fine at idle. This gives things a chance to lub up an warm up just a bit

 

[jenkinsph]

I run my tractor and backhoe anywhere from 1500 to 2400 rpm depending on the job at hand. Most digging up close to a building or pipe I don't want to tear up is at lower rpm's, transport up a long grade is 2400 rpms'.

The idea that you must run at pto speed to use all pto implements is a gross misunderstanding alot of people seem to have. Fewer people have the misunderstanding that you need to run a hydro tractor at high rpms' all the time. Lugging the motor and running at reduced rpms' are two different things.

 

[SPYDERLK]

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

Originally Posted by JDTank

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.

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.


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.

Fraid not. ... Hydraulic pumps leak internally somewhat. Amt of leakage is related to pressure and time. Higher revs allow less time to leak per revolution. Therefore delivery per revolution is greater at higher rpm. This becomes more pronounced as the hyd fluid thins with heat.
larry

 

[GManBart]

Fraid not. ... Hydraulic pumps leak internally somewhat. Amt of leakage is related to pressure and time. Higher revs allow less time to leak per revolution. Therefore delivery per revolution is greater at higher rpm. This becomes more pronounced as the hyd fluid thins with heat.
larry

Increased pressure would also increase the amount of leakage too, so it could cancel out at least some of the shorter time available to leak.

Unless somebody has tested a theory like this, or has access to actual data, I'm not buying it....or at least not buying that it makes a functional difference. The pumps have a bypass...as soon as the bypass starts to open, none of this stuff really matters, because the pump is already putting out full pressure, and volume.

Actual use of your machine can give you an idea when the bypass engages....anything above the RPM at which you see full lift, and the shortest cycle times. If increasing RPM doesn't decrease the cycle times, or increase the lifting ability, your pump is already putting out full pressure, and volume, and the bypass is engaging to prevent any additional increase.

 

[jenkinsph]

Fraid not. ... Hydraulic pumps leak internally somewhat. Amt of leakage is related to pressure and time. Higher revs allow less time to leak per revolution. Therefore delivery per revolution is greater at higher rpm. This becomes more pronounced as the hyd fluid thins with heat.
larry

I agree that higher rpms' will leak less per revolution but that doesn't mean it is necessary to run the tractor at WOT to use it in all cases. Continuous high pressure and poor cooling designs will wear out hydraulic gear pumps (open center) faster than most things. Correct me if I am wrong but I don't see where it is necessary to inch back to a new building form at pto speed simply because the tractor is moving a little.