Interesting Tug of War Scenario - Loco Vs. Monster Truck

It would be fun to see how it would play out between an SD70ACE and Caterpiller 797F.

The truck has almost 4000 hp and weighs 1,375,000 lbs. fully loaded. The traction has to be incredible with its huge tires, weight, and rubber-on-the-ground.

Two setups:
1. A very tight chain linking them.
or
2. A chain with a little slack.

The truck is made to haul, and the locomotive is made to pull.

I wonder which would win?


http://en.wikipedia.org/wiki/Caterpillar_797

The quick answer: “It depends”.

Here are calculations under a couple scenarios using data taken from the respective machine manufacturer's spec sheets.

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Situation #1 – Pulling against each other from a standstill.

SD70ACe: Max drawbar pull @ 0 mph = 191,000#

Cat 797F : Assume truck is fully loaded, 67% of total weight is carried on rear (drive) axle, coefficient of friction of tires to road is 0.9 (rubber tire on clean, smooth stone or concrete).
Max drawbar pull then is 1,375,000 x 0.67 x 0.9 = 829,000#

Here the truck easily outpulls the locomotive.

(Note this assumes the drive train/axle can handle full engine HP @ 0 mph - which is probably NOT true. Rather, HP in lower gears engine power is likely limited to prevent exceeding transmission & rear end torque handling capacity.)

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Situation #2 – Pulling against each other at 12 mph. (This assumes of course you have a suitable connection between them to allow a "running start" without destroying $10,000,000+ of machinery!):

SD70ACe: Continuous drawbar pull @ 12 mph = 157,000#

Cat 797F: Assume full net engine HP (3,793 hp) in 3rd gear @ 12 mph ( =17.6 ft/second)
Max drawbar pull then is 3,793hp x 550 ft-lb/hp / 17.6 ft/sec = 118,531#

The SD70 now EASILY walks away dragging the Cat!

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It would be fun to see how it would play out....

Indeed!

...FB

Thanks - great answer! Well thought out.

Hey, if the SD70ACe units have 191,000 lbs. of starting TE, and a weight of 420,000 lbs., does that mean that the adhesion is 45%?

Yup! 191,000# starting TE / 420,000# weight on driven wheels = 45% factor of adhesion

Incidentally 45% adhesion will only be achieved under ideal conditions: On clean/dry/sanded rail and with computer-controlled wheel slip system working.

...FB

FarmallBob wrote:SD70ACe: Continuous drawbar pull @ 12 mph = 157,000#

Its continuous TE may be 157000 lb for all I know, but that wouldn't be at 12 mph. (More like... 8 mph?)

Closer to 10.3 MPH, no?

The comparison between the two also illustrates why railroads are more efficient than trucks if you really want to move a lot of stuff over the same route. The truck has a fully loaded weight of 638 tons: I don't know how much of that is payload, but I'd guess under two thirds. So a 3700 hp truck will lug maybe about 400 tons. A 4300 horsepower locomotive, on the other hand, can easily pull a train of several thousand tons.
The main application of trucks like this, I think, is in mining: moving the coal or ore or whatnot out of the pit to a place where it can be dumped into hopper cars.

Allen Hazen wrote:The comparison between the two also illustrates why railroads are more efficient than trucks if you really want to move a lot of stuff over the same route. The truck has a fully loaded weight of 638 tons: I don't know how much of that is payload, but I'd guess under two thirds. So a 3700 hp truck will lug maybe about 400 tons. A 4300 horsepower locomotive, on the other hand, can easily pull a train of several thousand tons.
The main application of trucks like this, I think, is in mining: moving the coal or ore or whatnot out of the pit to a place where it can be dumped into hopper cars.

Well, but aren't there two different purposes here? A locomotive could never do what that truck is being used for, and vice versa.

I read on the GE page a while ago that a 4400 hp GEVO could pull 50,000,000 lbs. at 10 MPH on level ground. Of course there is no level ground, but still...

OK, so how about this: what if EMD or GE built their own diesel-electric haul trucks? Picture an "Evolution Series" haul truck with a 4400 HP GEVO-12 and GE AC traction motors powering big brawny rubber-tired wheels. Just think of what that bad boy could do!

MEC407 wrote:OK, so how about this: what if EMD or GE built their own diesel-electric haul trucks? Picture an "Evolution Series" haul truck with a 4400 HP GEVO-12 and GE AC traction motors powering big brawny rubber-tired wheels. Just think of what that bad boy could do!

EMD effectively does now that they share a parent company with Caterpillar. The 797F is already a 4000hp truck, though it uses a torque converter transmission. It's not likely there'd be any functional difference in power if it were built as diesel-electric. Many of the super sized trucks already are diesel-electric.

Denver Dude wrote:Closer to 10.3 MPH, no?

If it could produce 4300 hp at the rail, which we assume it can't. (None of us knows how efficient its transmission is.)

Denver Dude wrote:I read on the GE page a while ago that a 4400 hp GEVO could pull 50,000,000 lbs. at 10 MPH on level ground.

It can likely pull at least double that at 10 mph-- but if the train is stationary, could one GE start it rolling? That we don't know.

timz wrote:

Denver Dude wrote:I read on the GE page a while ago that a 4400 hp GEVO could pull 50,000,000 lbs. at 10 MPH on level ground.

It can likely pull at least double that at 10 mph-- but if the train is stationary, could one GE start it rolling? That we don't know.

With tight knuckles or with slack?