What Does Horsepower Really Mean

[JasperFrank]

I am somewhat suspicious of this since the tug IS pulling the truck off the dock at the beginning of the contest, but then the tug gets a bit sideways: Yet it is a fun Vid.

 

[Hay Dude]

Given equal rated HP engines for a tractor I will chose the one with Lower RPM for the same rated HP.
That means a Higher actual Measured torque.

Which generally is the heavier weight, Larger physical dimension engine which has a heavier crankshaft, pistons, and rods.
IMO these newer CUT tractors have decreased the mass, Increased the RPM of the diesel engine to achieve the rated HP.

I was semi-interested in a new Deutz-Fahr 140HP tractor last week, but the engine is only 4L and IMO, longevity and torque at low RPM would be questionable.
Although if anyone could figure out a way, it’d be German engineering.

 

[4570Man]

If I remember correctly ......... Mechanical horsepower is the ability to move 550 pounds one foot in one second. So a 20 horsepower engine would move 11,000 pounds 1 foot in a second.

Are we vertically lifting the 550 pounds which seems like the easiest to replicate measurement or dragging it? If it’s dragging it does it have wheels or skids?

 

[4570Man]

weight has a lot to do with this as well. How much does the john deere weight in comparison to that old steamer?

Weight and traction wins tug of wars. HP doesn’t really matter. Without increasing traction you could increase the hp by 10x without a big difference in the outcome. This is weight and traction at work. Think a pickup with 2x the hp could chain up and drags it?

 

[4570Man]

I am somewhat suspicious of this since the tug IS pulling the truck off the dock at the beginning of the contest, but then the tug gets a bit sideways: Yet it is a fun Vid.

There’s a lot to consider in that video besides just hp. Props aren’t as efficient as wheels for utilizing input power to start with. The truck weighs a lot more than the thrust that the boat can make. As with any tug of war the tow line should be level to really demonstrate anything. With so much elevation gain the boat is pulling the truck downward which increases the friction between the tires and the road. If the line was level the boat probably could have won. Also they obviously didn’t want to pull a million dollar truck in the ocean so the boat never had any chance of “winning”.

 

[BnRidge]

Brake Hp, PTO Hp, drawbar Hp, horsey Hp, all the same. It's the transmission package that changes.

Yes, but the transmission is a huge part of the tractor package.
Drawbar HP is measured at the end of the drawbar, taking into account losses through the driveline. Brake HP is at the flywheel and does not take transmission into account. So they are not the same.

Power transmission (transmitting power) includes far more than gear reduction, or a driveline, or drawbar. Power can be converted from many forms to many other forms - electric, electromechanical, mechanical, fluid, heat, with many different units of measure. In the end energy is conserved, so adding it all together will result in same power regardless. Maybe "transmission package" would be a little vague and misleading, but it has very little to do with shifting gears. How many BTU/hr does it take to pull a plow. I like looking at combines - one power source, so many ways to transmit power, and none of them include a drawbar.

 

[JasperFrank]

Horsepower = Torque x RPM / 5,252. The problem I have always had with this equation is the RPM component and how that is "fit in to" the equation. RPM and the division by 5,252 seems to be entirely unneeded. Torque is the one and only value that needs a measurement. HP can be anything you want it to be if the RPM is just set at any arbitrary value. Friends and I, discussed this for over 20 years on a Speed Boat site. HP just didn't make sense as any meaningful rating of power. A Saturn 5 rocket, on launch is said to have had 32 million horsepower. What does that even mean?

 

[sd455dan]

Horsepower = Torque x RPM / 5,252. The problem I have always had with this equation is the RPM component and how that is "fit in to" the equation. RPM and the division by 5,252 seems to be entirely unneeded. Torque is the one and only value that needs a measurement. HP can be anything you want it to be if the RPM is just set at any arbitrary value. Friends and I, discussed this for over 20 years on a Speed Boat site. HP just didn't make sense as any meaningful rating of power. A Saturn 5 rocket, on launch is said to have had 32 million horsepower. What does that even mean?

Right
HP to me means rate of work that can be done over time. Just a calculation
Torque being the resultant moment of force applied at a distance or basically its measured twisting force.

On the Saturn V 7.6 million lbf seems to convey more meaning than the HP
That said can't wait to see the launch of SpaceX Starship with it's 17 million + lbf.
Being able to lift over 100 tons of payload into space will be a Game changer

 

[bcp]

A Saturn 5 rocket, on launch is said to have had 32 million horsepower. What does that even mean?

Obviously, it means 32 million horses could have pulled it into orbit. And instead of so much pollution, the horses would produce useful fertilizer to grow more hay to fuel the next launch.

Just like two horses on a buggy can pull it twice as fast as one horse.



Bruce

 

[Fuddyduddy1952]

From what I looked up a healthy human is about 1.2 hp, athlete can be 2.5 hp. Next time I'm using my Weedeater I'll think about it has more power than me.

 

[4570Man]

From what I looked up a healthy human is about 1.2 hp, athlete can be 2.5 hp. Next time I'm using my Weedeater I'll think about it has more power than me.

And that’s only for a brief time. The several hour rating is only 2-300 watts which is about 1/3 hp. A weed wacker no doubt has more power than a human. Imagine the gear ratio it would take you to achieve the same rpm and how long you could maintain trying to turn it.

 

[Fuddyduddy1952]

Torque. It's all about torque. The best thing I ever put on my tractor was a winch. Nothing fancy...just a Harbor Freight one on sale. Sometimes I'll chain drawbar to a large tree, but so great ripping bushes up out of the ground or pulling large trees I cut down. Also pulling tractor out of mud.

 

[BnRidge]

On the first one minute human powered helicopter flight, the max first 10seconds were about 1100watts (1.5hp).
Atlas Human-Powered Helicopter - AHS Sikorsky Prize Flight

 

[4570Man]

Torque. It's all about torque. The best thing I ever put on my tractor was a winch. Nothing fancy...just a Harbor Freight one on sale. Sometimes I'll chain drawbar to a large tree, but so great ripping bushes up out of the ground or pulling large trees I cut down. Also pulling tractor out of mud.

You should be careful about pulling on opposite ends of a tractor like that. More than one tractor has been broke in half like that.

 

[Fuddyduddy1952]

Ok. Time for my true and funny story, it ties in with rpm and torque. I worked for two guys in 1972 who sold surplus electronics.
They bid on and once got 3 tractor trailer loads of stuff, all in boxes. Building was 38,000 sq.ft. It was like Christmas not knowing what you'd find.
One heavy item was round, about 18" diameter by 10" high and had two steel shafts either side on top. Inside was a bunch of gears, very well made, all with bearings. The label said "1000:1 gear reduction unit".
You could easily turn the one shaft, not the other. In the shop they had a 1/2" variable speed 0 to 1,200 rpm drill. I chucked it on drill and ran it wide open, flipped on it's side you could watch all the gears turning and other shaft going about 1 rpm.
That night I invited friends over, and my wife was there also. I connected the drill to the other shaft, then spray lubed everything.
It was amazing starting out very slow...building up speed. Finally drill was at full blast...1,200 rpm, but the last gear was turning over a million rpm!!!!!
That last gear was invisible as were some of the others, "only" turning 100K rpm or so.
Within minutes that final gear disintegrated.
Thinking about the gear's 6" circumference the gears edge was going at over Mach 10!

 

[Fuddyduddy1952]

You should be careful about pulling on opposite ends of a tractor like that. More than one tractor has been broke in half like that.

! Good point! I'll chain it to the winch...much better.

 

[mo1]

Yes, but the transmission is a huge part of the tractor package.
Drawbar HP is measured at the end of the drawbar, taking into account losses through the driveline. Brake HP is at the flywheel and does not take transmission into account. So they are not the same.

When buying a tractor, on the back end I want to know:
1. how much it will “drag” across the ground.
2. how much power is available at the PTO to run my baler, or whatever the user is running. (baler, sawmill, snowblower, etc)

View attachment 781145


IMO, on the back end of a tractor, what is most important is pulling power (drawbar HP) and PTO horsepower.

Here is the “Tests” page

View attachment 781146



On the front end (if loader equipped) what is most important is the lifting power of the hydraulics and the front axle capacity for carrying a load.

Any tractor buyer should consult Tractor Data and pay special attention to the “tests” page. Here you can compare what your tractors will actually do.

TractorData.com CaseIH MX270 Magnum tractor tests information

www.tractordata.com

****Unknown/unsupported brands aside, I urge all of you to stop buying “brands” and start buying “tests” when you come up with your lists of comparable models.****

The University of Nebraska's tests are very useful but only performed on some tractors, and generally not the ones most people here are looking at.

The University of Nebraska currently only does its full set of tests on tractors of over 100 PTO HP that are to be sold in Nebraska, per state law. If a manufacturer doesn't want to sell in Nebraska, they don't have to have their tractors tested. Tractors less than 100 PTO HP do not have to be tested to legally be sold in Nebraska but a manufacturer can voluntarily have them tested. It is rare to see anything smaller than a full-sized utility tractor tested today and even of those, it is generally only CNH and Deere that have theirs tested. The University of Nebraska will perform an abbreviated set of tests on <100 PTO HP tractors that does not test drawbar horsepower. They hook it up to a PTO dyno and determine maximum PTO power and fuel usage, they test hydraulic pressure and maximum flow, and test 3 point lift.

 

[edgarrian]

Weight and traction wins tug of wars. HP doesn’t really matter. Without increasing traction you could increase the hp by 10x without a big difference in the outcome. This is weight and traction at work. Think a pickup with 2x the hp could chain up and drags it?

Thats what i was getting at. The old steamer probably weighs twice or maybe three times as much as that deere.

 

[Hay Dude]

The University of Nebraska's tests are very useful but only performed on some tractors, and generally not the ones most people here are looking at.

The University of Nebraska currently only does its full set of tests on tractors of over 100 PTO HP that are to be sold in Nebraska, per state law. If a manufacturer doesn't want to sell in Nebraska, they don't have to have their tractors tested. Tractors less than 100 PTO HP do not have to be tested to legally be sold in Nebraska but a manufacturer can voluntarily have them tested. It is rare to see anything smaller than a full-sized utility tractor tested today and even of those, it is generally only CNH and Deere that have theirs tested. The University of Nebraska will perform an abbreviated set of tests on <100 PTO HP tractors that does not test drawbar horsepower. They hook it up to a PTO dyno and determine maximum PTO power and fuel usage, they test hydraulic pressure and maximum flow, and test 3 point lift.

Still, those tests can tell you a lot more than brand warfare comparisons.

 

[Fuddyduddy1952]

Back in the muscle car days some motors were overrated for sales but most underrated for insurance purposes. Some came from the factory detuned, small cfm carburetors, etc. to lower hp.