The most powerful traction engine on the grounds?

[Spencer the Great]

Ive watched the Rumley at the dyno and I believe it to be the most powerful engine at Rollag. Does anybody recall the boiler pressure? Secondly, could a ranking list be put together?
Spencer

[GaarScott]

Spencer,

While the strongest engine is certainly a debate I don't wish to get into...I would agree though, that the 36hp Rumely steamer is an impressive machine...both in presence and power. However, my understanding is that she got knocked down a little during last years MN inspection. So she isn't running up to full snuff. I still recall standing fifteen feet or so back from the engine back in 1992 when (name escapes me) put on a drawbar hp demonstration. I recall watching the Rumely slipping wheels and the ground beneath my feet shaking as she pulled to caterpillars with their brakes either locked or riding them. Can't recall that for sure. But the overall POWER was UNBELIEVABLE!:bannana:

Does anyone have the data from that pull. I recall speaking with the operator of the mighty Rumely a couple years back and we spoke about the intimite details then. But my mind gets a little foggy and I don't always recall all of the details accurately. So without putting my foot into it. Does anyone know for sure what the load was per lbs. - the time it took to do the pull - and the distance in which she traveled. Which is drawbar hp! Regardless, it was an impressive sight and I'm glad that I happened to stumble by at the right time.

My understanding is that Rollag won't repeat this demonstration for insurance reasons. Too bad, I recall it being a real crowd pleaser!

Lawrence

[Jerry Christiansen]

Hi Lawrence, Spencer and anyone else that reads this stuff,

The Rumley did indeed to a drawbar horsepower test several years ago when Amos R. was still with us. We haven't done drawbar testing lately for a couple reasons.

1) when doing drawbar testing we are putting a large load on the old, worn gears in the drive train. If one of those breaks, you can imagine the cost of repair. Because of this, many privately owned engines are not interested in drawbar testing. While belt testing for maximum horsepower pulls the enigne hard, no power is being transfered through the drive train.

2) If an engine is going to acheive maximum drawbar horsepower, there can be no slip between the wheels of the pull tractor and the ground. To reduce slippage, the Nebraska tests are on a very solid surface that reduces slippage to very low values. Modern rubber tires are tested on a concrete pad.

3) To test a modern tractor and measure it rated horsepower, the tractor has to be moving along at a (relatively speaking) high speed. This makes measurements with the equipment we have difficult.

4) If a Cat is being used as an anchor, the Cat operator has to operate the brakes so that a constant load is applied through the measured distance. This too is a difficult thing to do.

Because of the items above, most tractors that were measured got dissapointingly low horsepower numbers and the demonstration fell from favor.

We still have all the equipment needed to do such a demonstration at Rollag. If someone had an interest in running their tractor to demonstrate drawbar horsepower, we can do it. Be prepared for low values!!

Later,
Jerry Christiansen

[jasher]

The answer to the original question is easy-the 353!

[Spencer the Great]

The only traction engine I've seen do any pulling was the show's 75 case when it made a surprise appearance at the tractor pull ??last year?? my memory doesn't serve me well. I was more thinking along the lines of brake horsepower. Jerry what have you any your crew on the dyno determined?

[Spencer the Great]

there are a number of differnt measurments ive heard about from the rumley. A couple of years ago, when the belts were in better shape, they measured stall torque, the belt was flopping up and down violently but the announcer said that the engine was making 18000 ft/lbs at 25 rpm. The number sounds large and I'm not sure if he ment 1800 ft/lbs. (it would really be sweet if it was 18000 :D) This is complicated by the fact that i watched a youtube movie of it another time the anouncer said "After doing the math, the result was about 130 HP (97 kW) and 3,400 ft-lbs (4610 Nm) of torque."

I'm no longer sure of the point i was trying to make, I guess I'm just wondering if 18000 ft/lbs at 25 rpm is a valid and reasonable number.

[Spencer the Great]

K well i did some calculating- when the the Rumley made 130Hp and 3400 ft/lbs it did not give the rpm. By applying the formula Torque=horsepower*5252/rpm and imputing different rpms (i nearly flunked algebra, so i just crudely imputed numbers randomly: 300, 250, 200) i found that when the rpm is at 200, the torque is a little more the 3400...so those numbers are correct and valid. ~~known torque= 3400 ft/lbs ==EQUALS== (130hp times 5252) divided by unknown rpm. in my case the unknown rpm was 200, thus solving for the unknown.

This may seem very confusing and I agree, its got my mind all tied up, but I can't let it go until I figure it out! I hate math passionately and yet I'm using it grudgingly to find the answer; its really quite a feat!

so back to my account of the 18000 ft/lbs @ 25 rpm when those numbers are plugged 18000*25/5252 the result is 86 horsepower@ 25 rpm. This number must be wrong. Although the rumley is a massive engine, it simply cannot make 86 horsepower rotating that slowly while an 85 case runs on the governor at 250rpm

But on the other hand, it would make more sense if the engine made 8.6 horsepower@ 25 rpm, and this number is derived from taking a zero off 18000.

But this leads to a new problem - steam engines produce maximum torque at zero rpm, and as the rpm increases, the torque decreases. So now it begs the question- if the youtube movie shows the engine making a wopping 3400 ft/lbs at 200 rpm, how could that possibly be true. How could it only make 1800 ft/lbs @ 25, and yet when the rpm is increased to 200, the torque has jumped to 3400 ft/lbs ???!!!

for that reason alone, i believe the announcer must have been right in saying the Rumley produced 18000 ft/lbs @ 25rpm

I've been working on this post for little over an hour and i still don't know what I've proved!!! AHHH!

what is the opinion of the readers?

[GaarScott]

Spencer the Great,

Not to take away from brakehp...but if you ever have the opportunity to watch/feel the ol' Rumely laboring by while dragging two cat's behind her developing something like 70,000 lbs. line load (going off memory), then you may get a whole new perspective of the meaning of "power"! As impressive as the Rumely is on the brake, this big horse wasn't really known for its belt hp. But rather what she could do out in the field. As for explaing the difference between torque and hp...I will let Jerry C. do that, as he does an excellent job of doing so...even to a dense head like myself.:p

Jerry, what would be the chances of doing drawbar hp tests again? I'm sure that the Rollag group could come up with a more suitable accurate way of loading an engine. I sure would like to watch a demonstration like that again! Impressive!;)

Lawrence

[Jerry Christiansen]

Hi Spencer,

Let's take a look at the 18000ft*lb of torque and see if that makes sense. Then we will worry about horsepower.

Torque is force mulitplied by the length of the lever arm.

T = F X L

That means that Force would equal the Torque divided by the length of the arm.

F = T / L

= 18000ft*lb / 5.25ft (the lever arm on the Red Brake is 5.25ft.)

= 3428lb

That means the scale on the Red brake would have to read 3428lb. The scale can only read a maximum of 1500lb. (The dial goes up to 1000lbs and a sliding weight can add another 500lb).

so back to my account of the 18000 ft/lbs @ 25 rpm when those numbers are plugged 18000*25/5252 the result is 86 horsepower@ 25 rpm. This number must be wrong. Although the rumley is a massive engine, it simply cannot make 86 horsepower rotating that slowly while an 85 case runs on the governor at 250rpm


I agree with you, something is not making sense. If the Rumley could cause the scale to read 3428lb (which is 18000ft*lb of Torque) at 25rpm, then it would produce 86hp. I believe the 18000 is in error.

I can remember the Rumely getting the scale up to the 650lb range(3412ft*lb of Torque). If brake was still spinning at 250rpm, the Rumley would be producing 163hp

Hp = Force X rpm / 1000 (This formula works for our Brake because the lever arm is 5.25ft.)

= 650lb X 250rpm

= 163hp

Before you beat your head against the wall too hard, question the 18000 number.
I would believe the 3400ft*lb of torque at 200rpm. 3400ft*lb of torque divided by 5.25ft gives a force around 650lb. That is a number that I have seen for the Rumley on many occasions.

I have run the brake several times with th 40hp Avery on the belt. The most I have measured has been around 140hp. Mark K. has a sheet that Amos did some years ago that shows a maximum of 160hp. We have been wondering why we can't get that high of number.

I hope this answers some of your questions.

Later,
Jerry Christiansen

[GaarScott]

Jerry,

Thanks, I knew that you could eloquently explain the phenomenon known as "torque" in a more civilized manner than myself. Thanks.

Lawrence

[Jerry Christiansen]

Spencer the Great,

. . . . something like 70,000 lbs. line load (going off memory), then you may get a whole new perspective of the meaning of "power"! . . .


Lawrence

Even if the Rumley was pulling with 70,000lb of force, it still can't produce more power than what the engine can produce in the belt. The maximum theoretical (sp??) horespower of a steam engine can be predicted with the PLAN formula. Because of frictional losses, the belt horsepower will be less. Because of addtional frictional losses in the drive train and slippage between the tires and the ground, drawbar horsepower will be less than belt horsepower.

Maybe a better word to use in the sentence above would be torque. Our steam engines produce LARGE amounts of torque.

A modern diesel engine can produce the same horsepower as the Rumley, 160hp. If the diesel is spinning at 2500rpm (ten times the speed of the Rumley) it is only producing one-tenth the torque. Steam engines, including the 353, can start large loads because they produce high torque.

The Pabst Engine produces 600Hp at 125rpm. That means the Pabst engine produces around 25,000ft*lb of Torque.

Later,
Jerry Christiansen

[Spencer the Great]

Ahh I see. That pretty much answers all the questions I had. I've always wanted to see steam plowing, but I've never had any luck finding it. The 2007 show was the first time I saw it, but I was a 3 or 4 thousand feet away. What is the scoop with plowing schedules?

[Spencer the Great]

Thanks Jerry, that cleared it all up. One thing that I found interesting is that you mentioned that the lever arm is 5.25 feet long and now i realize that because of that all one needs to do is multiply by the number on the scale to get torque! It definitely makes things less confusing, and I seen that initially, I wouldn't have had to do nearly as much math. I'm sure 5.25 is no coincidence "5252"....;)

[JLGundersen]

Hi All,

After reading this thread, I realized that the answers to some of these questions were edited out of my 2007 Rumely steam tractor prony brake video. I had to shorten it up to comply with YouTube's 10 minute maximum clip length.
So I made a new video that includes the audio edited out of the original. In this video, Bill McCreery explains the drawbar HP test, the concept of horsepower, Prony Rig 101, boiler pressure, V8 equivalency, and much more. Enjoy the video.

http://www.youtube.com/watch?v=WhjTo0BpkCY

And Spencer,
The answer to your question about the Rumely's boiler pressure is as follows: Originally 175 PSI, but now limited to 132 PSI.

[M Kerkvliet]

Thanks for the video JL...

Bill does a good job explaining steam, and the operation of the Prony Brake.

[Spencer the Great]

Thanks for putting up that second part of the movie! Its definitely going to be added to my favorites list.