Why are some engines lashed up to run backwards?

jhemby2 · 03-01-2004, 05:02 AM

On long trains I noticed that the point engine always runs forward. (understandable) But 2nd or 3rd (or more) sometimes (but not always) are running backwards. Is this intentional or just the way they happen to be facing when lashed up? I hope there is a logical, technical answer.

J · 03-01-2004, 11:50 AM

Locomotives find themselves in consists in a variety of ways. Some are assembled at the point of origin and include enough units to provide the desired horsepower for a given train. At other times, locomotives are picked up or set off en route due to mechanical issues or the need to reposition power.

Where I worked, prioirity intermodal trains were dispatched with 3.5 horsepower per ton while bulk unit trains might get as little as .9 HPT. Using this formula, 3 SD40-2's would be assigned to an intermodal train weighing no more than 2500 tons while the same units might drag an 8000 ton grain train.

That said, the only unit needed to face forward is the lead unit (unless tailing units are to be set out en route and need to face a certain direction). Locomotives run fine in either direction and while the lead unit can run "in reverse," issues such as crew visibility (definately an issue with desk type controllers) and air quality in the cab make having the cab in front most convenient. SP used to have a full compliment of gyralights and snow plows at both ends of their units and some B30-7s even had an extra set of horns at the rear of the long hood.

It takes more time than you would think to break up consists and turn power on a wye or turntable so power is generally dispatched in whatever direction it happens to be facing.

Add in other variables such as the following and you can see why there is such a variety in locomotive consists.

The need to send entra units to another part of the railroad to balance power
The need to get units to a service location for inspections / maintenance
The need to replace a lead unit that has problems such as mechanical defects or a lact of required cab signal equipment

jhemby2 · 03-01-2004, 04:26 PM

Thanks for the reply, J. That was a well put explanation. I appreciate you taking the time to explain all that. I feel like I now know the correct answer from someone who knows. Thanks again, jhemby2

Ken Carr · 03-01-2004, 07:34 PM

Just to add to J's comments speaking with trainmasters of both BNSF and UP here and in California they relate that with the so few turn tables having the 2nd or 3rd engine running in reverse they use it on point on the return trip. This I have notice more since talking to these guys. A number of DPU's on W/B coal trains trains are the lead engine on the return. Ken

jhemby2 · 03-02-2004, 04:45 PM

Thanks for your added info, Ken. That reason makes a lot of sense. I'll start watching for return runs to see if I recognize any coming back forward that I saw earlier going backward. Thanks. jhemby2

tomt · 11-28-2006, 02:11 AM

Quote:

Originally Posted by J

Locomotives run fine in either direction

they look 'good' going 'backwards'

http://www.railpictures.net/viewphoto.php?id=114550

Gordon Graham · 11-28-2006, 04:17 AM

I have another question then , why Southern Railway and some railroads would prefer to run Long Hood Forward ? Or why they design the long hood as the front of the locomotives ?

KCR ( Kowlooon-Canton Railway ) in HK is a railroad that running Long Hood Forward when the turntable was still here . Nowadays , KCR would also assign locomoties which run Long Hood Forward to main freights .

jdirelan87 · 11-28-2006, 05:46 AM

Quote:

Originally Posted by Gordon Graham

I have another question then , why Southern Railway and some railroads would prefer to run Long Hood Forward ? Or why they design the long hood as the front of the locomotives ?

Southern, Norfolk & Western and early Norfolk Southern (no suprise there) use to run long hood foward because it was believed that style provided more safety to the crew during a head on (the same reasoning behind high hood units). Southern went as far as to have their control stands put in backwards. For the afford mentioned reasons, this partice has been pretty uncommon, althought it happens time to time on NS.

On NS, a Dash-9 running long hood forward is commonly called 'hammerhead style.' I've only seen it once and didn't get a picture, but really wish I had so I could put 'hammerhead style' in the remark box.

Tåg · 12-02-2006, 01:00 AM

It is also more convinent to the crews if you need to make a set out and run light power back to your train. Running longhood forward causes a really bad blind spot.

Over the summer we needed to make a setout in Salem. We left our train on the mainline I cut our spots away and I rode the tail car to the south switch at Salem, got off lined our spots into the yard track, and shoved our set out into the rail. (We had a P and W switch crew protect our shove.)

We then cut away, switched operating ends, did a consist brake test, and went back to our train light power. Unfortunatly our trailing unit (an old SP SD40-2T) was facing forward so we needed to run long hood forward. Making it quite a white knuckle afair going over all those crossings.

WembYard · 12-02-2006, 06:58 AM

Question please, I have often wondered why locos in America only have one cab whereas most European countries go for two cabs (except on switchers).
In the UK our class 20 locos only have one cab and usually work in pairs like this;

A similar situation exists with the class 121 in Ireland (sadly only two left in service now)

But these are actually GM products which CIE bought to "try out" in the early 1960's. Having decided that they liked them, they then ordered a further batch but specified a two cab version (and for all subsequent GM types for Ireland)

Gordon Graham · 12-02-2006, 08:44 AM

Umm ... Even we have pair locomotives ,
we still run long hood forward for both forward and backward .