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Rated RPM vs Max RPM

B

BDuke

New User
Silly question here, but could someone explain Rated RPM vs Max RPM as it pertains to diesel tractors?
Thanks!
 
For International tractors this is what the terms would mean.

Maximum speed is the high idle setting of the engine. It is the speed with the throttle in the fastest position with no load on the engine.

Rated speed is the speed at which the horse power is determined. It is usually the speed where the injection pump reaches maximum fuel delivery.

The injection pump may deliver more fuel per stroke as the rpms drop lower but due to the lower speed the total fuel per second is less.

Maximum overload speed is the rpms at which the injection pump is delivering the maximum fuel per stroke.
 
Rated rpm's is the speed at which the rated HP is made, which MIGHT be PTO speed. PTO HP is not measured at 540/1000 PTO rpm. It's measured with the throttle fully extended, and the rpm's pulled down until they're at rated speed. Max rpm is just that, the maximum rpm attainable at no load.
 
(quoted from post at 09:21:11 09/12/13) Rated rpm's is the speed at which the rated HP is made, which MIGHT be PTO speed. PTO HP is not measured at 540/1000 PTO rpm. It's measured with the throttle fully extended, and the rpm's pulled down until they're at rated speed.
Click to expand...

Nebraska test states different from you. Pto speed on a 4020 isn't wide open throttle but 2200 engine rpm.
mvphoto20534.jpg
 
That's right. And less than honest dealers will try to use most people's ignorance of that against them. When I traded my high-hour 9600 in on a TW35, the deal was contingent on it dynoing OK. When I got there, they had it on the dyno, and claimed it would only make 80-85 h.p. Showed me the reading with it at 2000 engine RPM. I told them to open the throttle...and then load it down to 1000 PTO RPM... made 140 h.p. (rated 135)
 
Why not show the whole page? Go read the test again. The crankshaft speed is 2200 rpm. On the right it says that the rated speed is 2200 rpm. If you look even further, you'll see where it says 'Belt Pulley' in bold. In that section it says Power take-off 1003 rpm at 1900 engine RPM. If it's like most tractors, 540 PTO rom will occur at a slower engine speed.
John Deere 4020 Diesel Nebraska Test
 
(quoted from post at 10:11:08 09/12/13) Why not show the whole page? Go read the test again. The crankshaft speed is 2200 rpm. On the right it says that the rated speed is 2200 rpm. If you look even further, you'll see where it says 'Belt Pulley' in bold. In that section it says Power take-off 1003 rpm at 1900 engine RPM. If it's like most tractors, 540 PTO rom will occur at a slower engine speed.
John Deere 4020 Diesel Nebraska Test
Click to expand...

farmer boy
I thought I showed the facts to what you were referring to. Now are you 100% sure belt pulley & pto speed require the same engine rpm's??? I think you'll find out 4020's achieve 540 pto rpm's @ 2200 engine rpm's!!!!!!!!!!
 

Read it again. "966 rpm at 1900 engine rpm
diam 12" face 8-1/2" Belt speed 3035 fpm [b:470e98e94c]Power
take-off 1003 rpm at 1900 engine rpm." [/b:470e98e94c]
The belt speed is 966 rpm at 1900rpm. The PTO speed is 1003rpm at 1900 rpm. Tractordata says that both 540 and 1000 PTO are acheived at 1900rpm. Nebraska confirms that without a doubt. Look up John Deere 4020 tachometer. The vast majority of the pictures show the PTO marking at around 1900rpm. Maybe some were made that did make 540 PTO rpm at 2200 engine rpm. Go back once again and take ANOTHER look at the Nebraska Test results. DIRECTLY below where it says 91.17hp at 2200rpm it
20537.jpg

See the info in the Green circle? That's what you need to look at.

This is getting off the topic at hand. I can tell you without a doubt that if PTO speed is acheived at rated rpm, it's a coincidence. It may have been designed that way, but there's nothing(SAE or ASAE) that say they must be the same.

20535.jpg

The picture is of the tachometer of a Kubota M6030. Rated engine rpm of 2400. PTO speed is 2000rpm.
 

farmer BOY
The area you have outlined in the green circle is to achieve 1000 rpm's on a 4020 but to achieve 540 rpm's one needs to operate engine at 2200 rpm's. Back in the hey day of the 4020 I would guess 75%+ pto equipment was operated at 540 rpm's. The way hp is measured has changed some since the inception of the Nebraska tests.

As far as Tractordata's concerned they have been known to make a mistake or 2 BUT they do provide a "wealth of information".
 
'At what engine RPM does the John Deere 4020 diesel acheive 540 PTO rpm as measured at the shaft'?

Let's end this thing. Thank You
 
AS I stated 2100 or 2200. I don't own a 4020 but I can sure take a photo of a 4020 tachometer. Here's a photo out of my 4255's operators manual. Be sure to read power at pto speed & rpms required(2200) Also note the governed speed range(800-2400 rpm's)
mvphoto20538.jpg
 
In the case of the 4255, rated rpm and the engine rpm required to attain 540 and 1000 rpm are all the same, according to the Nebraska test. The picture tells me nothing. HP available at the PTO, with the PTO spinning 540 or 1000rpm and HP available at the PTO while the engine is at rated speed are two different things, although in this case (4255) they are the same. In the case of the 4020, the two are different at 1000PTO rpm, and we have no proof one way or the other, except for tractordata, at what engine speed 540PTO rpm is acheived at. I'd love to see a picture of a 4020 diesel tach. It's unusual for 1000PTO rpm to occur at an engine rpm lower than 540PTO rpm occurs.

Let's look at another example. Allis 190XT/200. Considered a 93PTO HP tractor. It makes 93.64 HP at 2200 engine rpm. At 540 PTO rpm(1937 engine rpm), it makes 89.71 HP. TWO DIFFERENT NUMBERS, although they will cross at times.
 
The above post was supposed to have the Subject "JD Seller and other JD guys". Doesn't make a whole lot of sense otherwise.
 
We have a Kubota 126GX. I think fast idle and rated speed are the same. It will run 2350 wide open. The screen says it is putting out 100% power and the engine is still running 2350. 1000 pto rpm is 2200. It will put out 100% power before it pulls down any. Electronics has changed everything. Vic
 
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