Rated speed?
- Thread starter JRS
- Start date
Guessing it could be the speed of the engine in RPM's so that the PTO spins at 540 RPM...
ve9aa
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19thSF
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I saw it when I googled MX6000 specs:
- Engine: V2403CR-T.
- Type: CRS, direct injection, liquid cooled diesel.
- Engine gross SAE J1995 power: 63.4 HP (47.3 kW)
- Engine net SAE J1349 power: 59.5 HP (44.4 kW)
- PTO power: 51.7 HP (38.6 kW)
- No. of cylinders/Aspiration: 4 / Turbocharged.
- Total displacement: 148.6 cu. In. ( 2434 cm³)
- Rated speed: 2700 rmp.
armylifer
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jyoutz
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Interesting. Seems reasonable.
But I wonder if this is actually an accepted definition or an assumption?
I think the "Speed" part of the equation is what is debatable. Wonder if there is a formal definition somewhere...never was an issue in my mind though...
With a HST I just run my engine at whatever PTO speed seems right, and move the tractor forward at whatever speed seems right. No overthink here...
Well I worked on aircraft propulsion systems (mainly jet engines) as a propulsion engineer for 35 years so it would hardly be an assumption on my part.Interesting. Seems reasonable.
But I wonder if this is actually an accepted definition or an assumption?
I think the "Speed" part of the equation is what is debatable. Wonder if there is a formal definition somewhere...never was an issue in my mind though...
With a HST I just run my engine at whatever PTO speed seems right, and move the tractor forward at whatever speed seems right. No overthink here...
If you want more clarification, look at the SAE specs (SAE J1995, SAE J1349 There maybe some updated standards as my experience is somewhat dated) because these things are defined for use in engine specifications. The use of " speed" is part of the vernacular of "engine people" and means rpm not vehicle speed.
When someone tells you your tractor has a certain horsepower it is generally the max horsepower available for continuous use and is determined by a specific type of test. You my never use it but that's what the marketing people use to sell a tractor. The same is true of cars.
Airplane engines have several power ratings; take off rating which is generally time limited to 5 minutes, maximum continuous, maximum climb, maximum cruise.
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That was the point I was trying to make...I guess I was poor at expressing myself.
My point was that in the case of a HST tractor, speed is essentially independent of engine RPM, whereas proper implement operation often depends on correct engine RPM.
Rated "speed" implies speed of tractor movement, and one will have to look hard to find this rating published for a tractor, if even published at all. I guess one could argue that max speeds published could be considered maximum rated speed...not sure anybody really cares about this unless driving the tractor long distances.
Edit: I guess it boils down to what speed is defined as. Generally it seems that speed refers to vehicle movement. That is why a speedometer is called a speedometer. And a tachometer is not a speedometer...
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Greek "tachos" means speed, and "metron" means measure. Tachometer measures the speed of the engine, not the speed of the vehicle the engine is in. No, I'm not from ancient Greece, I google it because I was curiousEdit: I guess it boils down to what speed is defined as. Generally it seems that speed refers to vehicle movement. That is why a speedometer is called a speedometer. And a tachometer is not a speedometer...
rThat was the point I was trying to make...I guess I was poor at expressing myself.
My point was that in the case of a HST tractor, speed is essentially independent of engine RPM, whereas proper implement operation often depends on correct engine RPM.
Rated "speed" implies speed of tractor movement, and one will have to look hard to find this rating published for a tractor, if even published at all. I guess one could argue that max speeds published could be considered maximum rated speed...not sure anybody really cares about this unless driving the tractor long distances.
Edit: I guess it boils down to what speed is defined as. Generally it seems that speed refers to vehicle movement. That is why a speedometer is called a speedometer. And a tachometer is not a speedometer...
"My point was that in the case of a HST tractor, speed is essentially independent of engine RPM,......"
Say what! For motor vehicles, ground speed is a function of engine rpm, transmission gear ratio, rear axle ratio and tire diameter. Your HST is in principal a hydraulic pump coupled to a hydraulic motor connected to the rear axle and the drive wheels and the pump is driven by a diesel engine. HST stands for hydrostatic transmission. Can you explain your statement?
In the world I live in vehicle speed is not "rated".
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You seem to want to take issue with things rather than to simply understand the point being made.
With a gear tractor, for a given engine RPM you will get one ground speed which is a function of the overall gear ratio in the gear selected. You change ground speed by changing engine RPM.
With a HST tractor you set the engine RPM where you want and leave it there. YOU get any travel speed you want without changing engine RPM using the directional pedal. So with a HST tractor, ground speed is independent of engine RPM.
It is that simple. Not rocket science…
And if you change the engine speed on an hst, the ground speed changes. So ground speed is a function of rpm, but you chose to operate at fixed rpm. So be it. I can do the same thing on my geared tractors at constant rpm by shifting gears. I am limited by the ratios and an hst has a large range of ratios.
Rated speed is the rpm at which a power rating is achieved and has nothing to do with the ground speed. This was the OP's original question. End of story.
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But we digress. Rated speed refers to the rpm at which a power rating is achieved and has nothing to do with the ground speed. This was the Op's or.iginal question. End of story
