Tennessee Pass - 56,000 hp for 14,000 tons - why ?

Hi
my questions belongs to this photo and its description: http://railpictures.net/viewphoto.php?id=346594

100 car coal train with 35tons axel load (assumption) = 14,000 tons
7x10x3 engine arrangements = 55,950 hp

train weight to power = 0,25 tons/hp (or 4 hp/tons) *)
or only 5 coal cars per engine !!

eastbound coal train -> west side of mountain pass uphill, east side downhill
max grade : west side 3%, eastside 1.4% (wikipedia)

So they need the big amount of engines because of their horsepower for the mountain climbing part
and not their driven axles (minimum 80 motor axles) for dyn braking power during rolling downhill ?

Again; why arithmetical 5 cars/engine ?

Or was redundancy the reason why they use so many engines : Avoiding stalling uphill & runaway downhill ?
Did the engines run ever in notch 8 ? if yes, how is it possible that the train stay together they dont brake a knuckle ?

Bye



*)
just to compare:
Alaska RR:
10,765 tons / 24,000 hp = 0.44 tons/hp or 2.23 hp/tons --> http://www.railpictures.net/viewphoto.php?id=345955 --> but also 3% grade & sharp curves ...

other:
20,000 tons / 08.700 hp = 2.29 tons/hp --> http://www.railpictures.net/viewphoto.php?id=202733
11,133 tons / 06,000 hp = 1.85 tons/hp --> http://www.railpictures.net/viewphoto.php?id=335504
20,000 tons / 17.600 hp = 1.13 tons/hp --> http://www.railpictures.net/viewphoto.php?id=329564
11,740 tons / 17.200 hp = 0.68 tons/hp --> http://www.railpictures.net/viewphoto.php?id=334451
4 hp/tons == 0.25 tons/hp !! hot train for cold load UP/CSX reefer train --> http://www.railpictures.net/viewphoto.php?id=314207

My only guess could be deadheading or brake control. If the pass is steep/curved steeply, controlling the train could have been an issue, & they didn't want to take any risks.

My friend who works for BNSF says some of those extra locomotives would usually be thrown in back in the day if something was having issues, too far from repair facility or such, so if the traction motors or something have an issue you have a backup, both for a true backup, but also if one of them couldn't go full throttle or other similar issues, that way the locomotive is still making money before it comes in for a repair. No sure of they do this anymore though. I know I've seen Penn central trains with many locomotives on the front because along the way some of them would die and have to be shut down or whatever the term is.

They're not breaking knuckles because there are three sets of engines to this train. The lead set pictured, a mid-train set, and a rear-of-train set.

The high HP/ton ratio is to keep the train moving on a very steep mountain railroad, that is somewhat steeper than 3% for short stretches.

The power would have been in Notch 8 by the time the mid-train helpers started up the grade, and would have stayed at full power until reaching the top.

-Micah

To keep a train moving at a given speed, every time you add one per cent of grade you double the horsepower of the locomotive to maintain that same rate of speed.

Although I was a little too young to have visited during its heydey, everything I've researched over the years suggests that there were very few "statndard operating procedures" over Tennessee Pass.

Back in the April, 1963 issue, Trains featured "Minturn Memories", a first-hand account by Robert LeMassena describing a ride over the pass on a seasonal Eastbound fruit movememt involving three 2-8-8-2 helpers, in addition to the road power. Billed as "56 drivers and 56 cars of peaches" it was a tale not soon forgotten.

And a D&RGW ETT from the late 1940's in my collection shows only eastbound freight movements scheduled over the Royal Gorge route, plus the one daily passenger run of the Senic Limited in each diection. Apparently, the westbound traffic, presumably with empties predominating, simply moved as the crews and power from the scheduled eastbound runs became available.

It must have been an intriguing show to watch .... preferably from the magnificent isolation of the local CTC controlled from a "tower" at the top of the pass.

.Taurus. wrote:Hi
my questions belongs to this photo and its description: http://railpictures.net/viewphoto.php?id=346594

100 car coal train with 35tons axel load (assumption) = 14,000 tons
7x10x3 engine arrangements = 55,950 hp

train weight to power = 0,25 tons/hp (or 4 hp/tons) *)
or only 5 coal cars per engine !!

eastbound coal train -> west side of mountain pass uphill, east side downhill
max grade : west side 3%, eastside 1.4% (wikipedia)

So they need the big amount of engines because of their horsepower for the mountain climbing part
and not their driven axles (minimum 80 motor axles) for dyn braking power during rolling downhill ?

Again; why arithmetical 5 cars/engine ?



Or was redundancy the reason why they use so many engines : Avoiding stalling uphill & runaway downhill ?
Did the engines run ever in notch 8 ? if yes, how is it possible that the train stay together they dont brake a knuckle ?

Bye

They need all that many locomotives in the first photograph for their pulling power at low speed. Many of the locomotives listed for the leading group were built in the mid-60's and have DC traction motors and poor traction control equipment. All of them are Bo-Bo locomotives and so have more horsepower than they can convert into low speed pulling power. By contrast all of the locomotives in the Alaska RR photograph are modern Co-Co locomotives with 3-phase asynchronous AC induction motors, able to maintain a low speed pull with a low likelihood of the wheels slipping . The first photograph was taken in 1981, while the second was taken in 2010, the technology of locomotive control equipment has progressed a lot in nearly 30 years.

*)
just to compare:
Alaska RR:
10,765 tons / 24,000 hp = 0.44 tons/hp or 2.23 hp/tons --> http://www.railpictures.net/viewphoto.php?id=345955 --> but also 3% grade & sharp curves ...

other:
20,000 tons / 08.700 hp = 2.29 tons/hp --> http://www.railpictures.net/viewphoto.php?id=202733
11,133 tons / 06,000 hp = 1.85 tons/hp --> http://www.railpictures.net/viewphoto.php?id=335504
20,000 tons / 17.600 hp = 1.13 tons/hp --> http://www.railpictures.net/viewphoto.php?id=329564
11,740 tons / 17.200 hp = 0.68 tons/hp --> http://www.railpictures.net/viewphoto.php?id=334451
4 hp/tons == 0.25 tons/hp !! hot train for cold load UP/CSX reefer train --> http://www.railpictures.net/viewphoto.php?id=314207