Smokey Mountain Wrote:
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> I have noticed on the Smoky Mountain Railroad as
> well as the Western Maryland Scenic that they are
> using diesel helpers on the rear end of their
> steam powered passenger trains. On the Smokey
> Mountain RR the diesels were definitely assisting
> the train while the steam engine was leading the
> front end. On the Western Maryland Scenic the
> diesel have been in idle mode. A few years ago
> Amtrak ran special trains to Sears Point Raceway
> on the NWP line in CA. They ran one loco on the
> front and one on the back. I believe both engines
> were working. Is this a new trend and is it legal
> to have diesel pushers on the rear end assisting a
> passenger train in a non-emergency situation?
> Thank-you in advance.

Yes, helpers have been at one time or another used on the "rear end", albeit rarely in the "modern" diesel passenger era of the last 60 or so years. Helpers should be differentiated from Push/Pull operations. Helpers are added to a consist or train to help with gradient by adding more hpt (horsepower per ton) to maintain a higher operating speed. And yes, this is and was occasionally still done with passengers trrains, although rarer than ever these days, and usually it involves a power problem and they add and engine for the whole trip.

I once ran helpers on the Ringling Bros circus train, both on the branches, and over Beaumont. The circus trains is/was much longer than Amtrak and much heavier. I ran on the head end over Beaumont, and I ran as one of two switchers on both ends of the circus train from Long Beach to the LA Colesium on today's Expo line. Part of the way I was the pusher, and going back out on the the Santa Monica Branch, I was the puller, when we changed ends for air brakes, and changed direction.
'
Push-pull with an engine at both ends, is not generally considered to be a "helper" (added for a specific power need for gradient) ,it is part of the consist just as a cab car is, only with an actual engine, that can operate powered or unpowered depending on power needs and train size.

This two engine push/pull mode of operation is what you saw at the races, with probably a double normal sized train consist. As was the case with the circus train, it was just easier to have another engine both ends for the larger consist and for operation to have an engine at both ends. Brightline does this for horsepower, acceleration, ease of operation, and safety in it's standard train configuration for it's Florida operations. it is alos used by some transit agencies for all of those same reasons.

It is against no law of physics or the FRA that I know of proscribing double ended power consist like Brightline uses, although with certain passenger cars or any cars of certain weights, helpers were sometimes proscribed from rear end pushing. SP had a number of incidents, as more powerful diesel helper consists came along, of literally pushing the much lighter cabooses, off of the rails, and thus had to be cut in ahead of the lighter cabooses. Empty pigs and the like have similar pushing "L over V" characteristics, when too much power can push them off of the rails.

Steam helpers pushed and pulled passenger trains, as well. More so when locos were not a powerful and helper districts were at places like San Fernando, Pomona, or Acolita, complete with there own helper turntables, or wye to turn helpers.

The Santa Fe Second District (today's Gold Line) was so steep, that stean helpers on the head end, were helper F3's on the Chief into the mid 1950's, that cut out at Lamanda Park, which had once had a wye (for smaller"1890's" engines), but by the 50's would just cut out and run "light engine" backwards to Redondo after helping the train up the Arroyo Seco. There are a number of famous shots of 2900's pulling four unit F3's over the Arroyo Seco high bridge

And, places like Beaumont, which had it's own helper roundhouse until more powerful steam in the 1910's. 

Helpers, pushing or pulling are for more power needed to move the tonnage to overcome the grades (passenger or freight)... Push pull used for various operational reasons...

If there are grades on a tourist railroad, it may be for both reasons...

Helpers and push/pull 101... I hope that helped...