Nebraska tractor tests

mrashwood

Member
How in the world do they figure drawbar horsepower? I was comparing an Oliver 2150 to an IH 1466. The 14 has 123 drawbar HP but max pull is 13,673. The 21 has only 109 but pulls 16,509... Probably some highly scientifical computations... Who has run both? Which one would do more work or pull bigger equipment in the field? Just to start, the Oliver is way more awesome.
 
Horsepower is defined as the rate of performing work. One horsepower equals 33,000 foot-pounds of work per minute?that is, the power necessary to lift a total mass of 33,000 pounds one foot in one minute.
 
Drawbar horsepower is pounds (force) of pull times mph divided by 375. (The 375 is just a conversion
factor for the units.) Work can be done the fastest at the speed and pull combination that results in the
maximum power, not the maximum pull. A big max pull number is largely driven by heavy ballasting and low
gearing but nothing can make up for a lack of power.
 
tractor data is where I got those numbers. They usually seem correct. The drawbar number seems like a big drop off from the engine or PTO number. The drawbar horsepower is 22 less than the PTO on both tractors.
 
Drawbar HP is calculated by multiplying measured pull in pounds X measured speed in feet per minutes and dividing that total by 33,000 Ft-Lb per minute - Horse Power.

FYI, 1 Mile per Hour is 88 Feet per Minute.

In your example, check the speeds. the 14 is likely pulling 13,673 pounds at a faster speed than the 21 pulls 16,509 pounds.
 
The information on Tractor Data is not always 100 percent accurate or complete. I would look at the actual Nebraska Tractor Test for each tractor.
 
I remember when I was in Vo-Ag class 60 years ago we had a guest speaker come in and explain the Nebraska test. He used a John Deere 520 as his example and us boys all got a copy of the test so we could follow along. That tractor and dad was looking at one developed its maximum drawbar horsepower in either 5th or 6th gear because of the amount of work done, pounds pull & tractor speed, not what dad wanted to plow with In the lower gears pounds of pull was up but Horse power was down.
 
With stationary PTO power measurements there is no power being consumed in actually moving the tractor.
Also, transmitting power through the tires to the ground is inefficient compared to the PTO shaft.
 
Sure, it will pull that plow at 12 MPH, but how many horses will it take to pull your Dad's foot out of your butt?
 
ss55, you are right about the speeds. The 1466 was running faster at both max pull and max drawbar horsepower....The 2150 is still cooler... :D
 
That reminds me of the manual for my 86 series IH. It says that ground engaging equipment should be pulled as fast as the tractor will allow (or
words to that effect). I laughed when I read that. Clearly not written by someone who has planted a field after the field cultivator was pulled
through it at 50 miles an hour.
 
I was taught in physics, power is equal to force times distance divided by
time

James Watt invented the term horse power to sell his steam engine.

Force in pounds x distance in feet divided by time in seconds = ft x #/sec

550 ft lb/1 second = 1 hp

Another way to look at horse power is pulling force x speed (feet/second)

So it simple, want more pulling force, go slower. Less pulling force go
faster.

Got it, shift gears. Simple physics.

george.
 
To measure drawbar horsepower ya need a drawbar dynomometer.

Power is the rate at which work is performed. And work is defined as applying a force through a distance. So to measure work, we need to measure force and and distance. To measure power, we need to also measure elapsed time. (If we measure speed, we're measuring both time AND distance.)

Power equals (force x distance) / time. In the metric system, it has units of newton-meters per second, one N-m/s is one watt. In the English system, power has units of foot-pounds per second; to convert ft-lb/s to horsepower we divide by 550.

So to make a drawbar dynomometer we need to measure both the force applied to the implement as well as the speed at which it's pulled. The force can be measured by inserting a load cell between the drawbar and implement. The speed needs to be measured by an independent speedometer, say a wheel attached to the tractor or implement. The tractor's tach/speedo can't be used because of tire slippage.

With tractor and implement instrumented for drawbar force and speed, it's simply a matter of pulling the implement and measuring force and speed. The test would be run in each gear, and the load increased until peak horsepower is attained in that gear. Effective drawbar horsepower is normally greatest in the higher gears, because there is less tire slippage the higher the gear.

I suspect UNL started out using standard implements to do drawbar horsepower tests, then switched to dedicated devices. If you go to the <a href=http://tractortestlab.unl.edu/">Nebraska Tractor Test home page</a>, you'll see pictures of their current drawbar dynomometer, or "test car" as they call it.

Drawbar horsepower testing by UNL certainly affected tractor manufacturing. It's easy enough to measure PTO horsepower, but drawbar HP is difficult to measure and consequently very easy for manufacturers to lie about.

As for the odd results on tractordata.com, you should always go to the source, because Tractordata seems to just pick numbers at random. You can find the older reports in PDF by googling the particular tractor model plus "tractor test".

The Oliver 2150 test may be found here: <a href="http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1571&context=tractormuseumlit">http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1571&context=tractormuseumlit</a>

There are two tests for the IH1466; the later one (which seems to be the one used by tractordata) is here:<a href="http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2494&context=tractormuseumlit">http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2494&context=tractormuseumlit</a>

We see that for the Oliver, it has 16509 pounds of drawbar force in first gear overdrive. But it's only generating 87 drawbar horsepower, because it's only going 2 mph! Its maximum drawbar horsepower, 115 hp, is reached in 4th gear underdrive, where it's pulling 8981 pounds at 4.79 mph.

In the case of the Farmall, it has 13673 pounds of drawbar force in 5th gear (3 Lo TA), at a speed of 3 mph. If we pick a gear comparable to the Ollie's max drawbar horsepower, we find it will pull 8954 pounds at 5.32 mph in 8th gear (1 Hi TA), for a whopping 127 horsepower. Clearly the 1466 is the winner by a YUGE margin.
 
Home town had a Oliver dealer, so there was 7 or 8 2150's in the area. We had a '69 4wd that I put several hundred hrs. on. 109 on the drawbar does not seem right to me. I can remember Oliver service tech was sent to the dealer and ran some test on the Her. engine and ours was putting out just over 170 hp....Oliver did not like that and turned it back closer to 145.
Never been around a 14 IH...by the way, there are 2 2150's still there and being used on occasion.
 
Hi Peter,

I don't think the figures you've published on TractorData are incorrect, per se. But I do think by publishing only a small subset of the UNL data out of context, readers of TractorData can be led to incorrect conclusions.

Let's take for example the original poster's question. He was trying to reconcile why an Oliver 2150, rated at 109 drawbar horsepower, pulls 16,509 lbs, while an IH 1466, rated at 123 drawbar hp only pulls only 13,673 lbs. The answer, once one goes to the UNL test data, is obvious: The ratings are all taken at different speeds.

Oliver 2150 drawbar hp: 109.28 hp @ 3.43 mph
Oliver 2150 drawbar pull: 16,509 lbs @ 1.97 mph
IH 1466 drawbar hp: 123.2 hp @ 5.31 mph
IH 1466 drawbar pull: 13,673 @ 3.23 mph

My suggestion would be to include the groundspeed when reporting drawbar pull and horsepower. That way, a reader of your site will recognize when they're comparing apples and oranges, which should encourage them to seek out the source UNL test report.
 
Mark,

Thank you for the feedback. I do provide a direct link to the UNL test report in all of my summaries. I have been considering changes to how I report the drawbar data and will certainly incorporate your suggestions.

The other big difference between those two is ballasting. The IH 1466 has a heavier base weight, but was only ballasted to 16,650 pounds. The Oliver was loaded up to 21,125 pounds for the test.

In that era, ballasting was at the discretion of the manufacturer. The current OECD test rules do not allow ballasting.
 

neb test no 1125.. int 1466 weight added up to a test wight of 16660 lbs. with duals and wheel ballast... max output of 123.2 drawbar hp. tractor pulled 8700 lbs on a 2 hour test at 5.31 mph with a tire slippage of 6.92% does not say what percentage of hp was used for the two hour test. However the ten hour test was done at a more realistic 75% of max hp.at 6709 lbs of pull using 100.58 hp for this test.


pto tested 145.85 hp.
 


neb test 986 oliver 2150 tractor oct 1968...

tractor weight was 12990 lbs but WAS BALLASTED TO 21275 LBS for a two hour test to show 109.51 drawbar hp pulling 8590 lbs at 5.19% slippage.
 

IS the 21275 lbs a misprint??? how many tractors can carry almost double the weight w ballast.
taken from my neb tractor test book. I looked 4 times at it...
 
(quoted from post at 11:49:03 01/16/17) Hi Peter,

I don't think the figures you've published on TractorData are incorrect, per se. But I do think by publishing only a small subset of the UNL data out of context, readers of TractorData can be led to incorrect conclusions.

Let's take for example the original poster's question. He was trying to reconcile why an Oliver 2150, rated at 109 drawbar horsepower, pulls 16,509 lbs, while an IH 1466, rated at 123 drawbar hp only pulls only 13,673 lbs. The answer, once one goes to the UNL test data, is obvious: The ratings are all taken at different speeds.

Oliver 2150 drawbar hp: 109.28 hp @ 3.43 mph
Oliver 2150 drawbar pull: 16,509 lbs @ 1.97 mph
IH 1466 drawbar hp: 123.2 hp @ 5.31 mph
IH 1466 drawbar pull: 13,673 @ 3.23 mph

My suggestion would be to include the groundspeed when reporting drawbar pull and horsepower. That way, a reader of your site will recognize when they're comparing apples and oranges, which should encourage them to seek out the source UNL test report.
ARKB_MI, I went back and looked at the speeds and it does explain a lot. I would not be putting out much HP...I work steady but reeealllyyy slow. LOL! My brother has a 1466 and he makes fun of my 1850 and 770. So someday imma get a 2150 to drag his 14 around backwards!! I'll just have to make sure I get the weight right and pick the correct gear...
 

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