General Discussion (Model Railroader)

I hope this may be of some help.  I got this info from TRAINS magazine.  Correct me if my info is inaccurate.

Modern EMD and GE hood freight locomotives that are built for Class 1 North American railroads (such as BNSF) are "usually" geared for a maximum speed of 70 mph.  However, you'll rarely see an American freight train at that speed today as much more fuel is consumed at those engine rpms. 

Since there's high density of traffic on mainlines today, frequent stops/delays are the norm, so 70mph running is impractical in most cases.  The majority of long haul freight trains run at maximum speeds of 60 mph.    

There are excepetions. There are a few "hot shot" intermodals trains that will run at 70mph on designated lines.  For these trains, there usually a batch or pool of locomotives equipped with the gear ratios that permit the higher speed runs with less of a major impact on fuel consumption.  Union Pacific has or had a batch of locomotives for just such a service. 

Four axle units, especially EMDs, can take off faster than their longer six axle brethren.  Rio Grande's famous short and fast "Rail Blazer" freight runs almost always used 4 axle EMD Geeps because of their "get up and accelerate" abilities.     

Freight trains did run faster in the past. The Santa Fe Super C of the early 1970s ran at 70mph, however I read an article where locomotive engineers pushed that train to 85mph. That was impressive! 

On distance travelled in a time frame,  from MR many years ago and applied to my own layout, in HO, the  number or inches travelled in 5 seconds is the number of scale miles per hour.  Therefore  as someone here quite rightly said, 1 foot in 12 seconds is  the same as 30 inches in 5 seconds = 30 smph.

I have a more detailed explanation on my website and a method of tracking scale speed using markers.

http://www.xdford.digitalzones.com/modelrr10.htm

Most modern locomotives cannot maintain a low speed because of their gearing so as someone else made the point about 7 mph is about the minimum a loco can maintain light engine is about5-8mph depending on its horsepower. An engine will travel slower under load while overcoming its own inertia and that of its train. Up to about 70mph is usually within reason for a train as you describe!

Good luck and let me know how you get on!

Regards from down under

Trevor 

On distance travelled in a time frame,  from MR many years ago and applied to my own layout, in HO, the  number or inches travelled in 5 seconds is the number of scale miles per hour.  Therefore  as someone here quite rightly said, 1 foot in 12 seconds is  the same as 30 inches in 5 seconds = 30 smph.

Huh? I foot in 12 seconds = 1 inch/second. 30 inches in 5 seconds = 6 inch/second. How are they the same? 1 inch/second is actually about 5 scale mph in HO.

Andre

Well they will run slow and very nicely at that.

  I unload unit coal trains for a living and SD70's and AC4400's and ES44AC's all run for an 8 hour shift at less than .38 mph pulling the train thru the dumper smooth enough to spot each car within + or _   4" for all 125 cars.

This is done with the  slow speed switch enabled. A neat feature on all of em. Set it for 0.38mph and thats what ya get automactically every time you put the reverser in forward and throttle in 1. 

 They are not geared. They use electricity to drive a variable electric tractive motor that is within its range infininitly variable it seems.

DOUBLEJK,

   Actually, YES they do have gears, there is a gear set with a smaller gear on the traction motor and a larger gear on the axle on each axle. There are various combinations available, depending on the use, and maximum speed intended for the locomotive. The gear ratios are fixed and require a drop table to change, it is not something done on a whim and the gearing is not variable like a car or truck transmission. But there are gears between the traction motors and the axles, which give I believe roughly a 4:1 reduction. I am not positive, but I believe that one combination that I have read of was a 15 tooth traction motor gear and a 61 or 62 tooth axle gear. Maybe Railway Man will chime in with more accurate info, he is an EXCELLENT source on the 1:1 scale equipment.

                                         Doug

Andrechapelon quoted me ..."On distance travelled in a time frame, from MR many years ago and applied to my own layout, in HO, the number or inches travelled in 5 seconds is the number of scale miles per hour. Therefore as someone here quite rightly said, 1 foot in 12 seconds is the same as 30 inches in 5 seconds = 30 smph."

Andrechapelon, you are quite right chiding me that there was an ingongruent statement so please let me correct it while I am fighting off a flu type thing .  

WHAT I SHOULD HAVE SAID... 

I meant to say ... 12inches in 2 seconds (not 12) is the same as 30 inches in 5 seconds (multiply both by 2.5). 60 inches would be 60smph,  12 inches in 5 seconds would be 12 smph etc... Don't worry about the calculations as it is about 1% wrong... neither here nor there!

Thanks for the correction and I did not mean to make that mistake nor intend to mislead.

Regards from Down Under

Trevor 

challenger3980 wrote:

DOUBLEJK,    Actually, YES they do have gears, there is a gear set with a smaller gear on the traction motor and a larger gear on the axle on each axle. There are various combinations available, depending on the use, and maximum speed intended for the locomotive. The gear ratios are fixed and require a drop table to change, it is not something done on a whim and the gearing is not variable like a car or truck transmission. But there are gears between the traction motors and the axles, which give I believe roughly a 4:1 reduction. I am not positive, but I believe that one combination that I have read of was a 15 tooth traction motor gear and a 61 or 62 tooth axle gear. Maybe Railway Man will chime in with more accurate info, he is an EXCELLENT source on the 1:1 scale equipment.                                          Doug

This is true. While not a locomotive  specialist, I was hired by a locomotive rebuild or repair out fit from Illinois back when the Rock Island ceased operations, as a crane operator in the Kansas City yard. I loaded trucks with all the loco parts and gearing was explained to me by an employee of that company. The gearing is not like a transmission, but more like the rear end gearing in an automobile or truck. The "gearing" would govern the top speed, but is used mainly to control the HP that is transfered to the track. In other words, tall gears- less HP, but high speed. Short or low gears- more HP, but slow speed. Ken

snagletooth wrote:

train lover12 wrote:  Darth Santa Fe wrote:  train lover12 wrote: it has 2 trucks with 4 wheels each Alright, then you probably have a GP. The only other thing a 4-axle BNSF diesel could be is a DASH 8-40B. Here are links to a couple pictures, so you can know what the differences are. GP38, http://railpictures.net/viewphoto.php?id=220697&nseq=4 8-40B, http://railpictures.net/viewphoto.php?id=173965&nseq=23 it doesnt look like either actually its made by walthers trainline the number on the side of the cab is 3820 hope this helps a bit I just looked it up. It's Walther's Trainline GP9M in BNSF Pumkin Scheme,  road #3820. I'd link to it, but don't know how.

Here's a link to what I found on Google. I think it's a modified GP-7u.

http://www.rrpicturearchives.net/showPicture.aspx?id=25496

AltoonaRailroader wrote:

snagletooth wrote:  train lover12 wrote:  Darth Santa Fe wrote:  train lover12 wrote: it has 2 trucks with 4 wheels each Alright, then you probably have a GP. The only other thing a 4-axle BNSF diesel could be is a DASH 8-40B. Here are links to a couple pictures, so you can know what the differences are. GP38, http://railpictures.net/viewphoto.php?id=220697&nseq=4 8-40B, http://railpictures.net/viewphoto.php?id=173965&nseq=23 it doesnt look like either actually its made by walthers trainline the number on the side of the cab is 3820 hope this helps a bit I just looked it up. It's Walther's Trainline GP9M in BNSF Pumkin Scheme,  road #3820. I'd link to it, but don't know how. Here's a link to what I found on Google. I think it's a modified GP-7u. http://www.rrpicturearchives.net/showPicture.aspx?id=25496

nope the top gets wider in the back and this question has been answered already.

I didn't state the gear bit very well.

Yes locomotive's have a pinion gear on the motors armature shaft and a bull gear on the axle.

What I meant is you do not control speed with gears like in your vehicle having 1st gear 10mph max 2nd gear 20mph max etc.

You can't change or shift gears in a locomotive its fixed 1 set is all you got and it will run from 0 to top speed with that one gear ratio.