Seen a container train go by yesterday and had an engine up front, one in the middle and then the pusher at the end. What is the reasoning?

In the good old days, not too long ago, all 3 of these engines would have been up front. Then I have seen engine up front and one in the middle or a pusher, but not all 3 like that split up.

Thanks

 

 

Mark the "YARDMASTER"

BUTLER, WI

 

If you can read this, thank a teacher. If you are reading it in English, thank a soldier.

Original Post

For one thing, coupler forces and internal forces through the cars are lowest when the power is distributed throughout the train. This lessens the likelihood of a break-up or derailment.

MELGAR

Yardmaster posted:

Seen a container train go by yesterday and had an engine up front, one in the middle and then the pusher at the end. What is the reasoning?

Far smoother train handling with DPUs spread throughout the train. Slack action and coupler stresses are greatly reduced. Such train make-us are generally not possible with unit coal trains, due to the "flood loading on the move" at the coal mines, and unloading operations at the power plants. However, for most all other long freight trains, motive power distributed through-out the train, all radio controlled by the Engineer up front, is the best way.

In the good old days, not too long ago, all 3 of these engines would have been up front.

That was prior to the use of DPU (Distributed Power Units) radio controlled locomotives.

Then I have seen engine up front and one in the middle or a pusher, but not all 3 like that split up.

Thanks

 

 

Hot Water posted:
Yardmaster posted:

Seen a container train go by yesterday and had an engine up front, one in the middle and then the pusher at the end. What is the reasoning?

Far smoother train handling with DPUs spread throughout the train. Slack action and coupler stresses are greatly reduced. Such train make-us are generally not possible with unit coal trains, due to the "flood loading on the move" at the coal mines, and unloading operations at the power plants. However, for most all other long freight trains, motive power distributed through-out the train, all radio controlled by the Engineer up front, is the best way.

In the good old days, not too long ago, all 3 of these engines would have been up front.

That was prior to the use of DPU (Distributed Power Units) radio controlled locomotives.

Then I have seen engine up front and one in the middle or a pusher, but not all 3 like that split up.

Thanks

 

 

I always wondered why the DPUs were not used on coal trains.. Thanks HW!!

CFO, Construction Superintendent; Clinch River, and Southern RR.. (The CRS O Gauge Line)

TCA #19-744637

Woodson posted:

I always wondered why the DPUs were not used on coal trains.. Thanks HW!!

They are used pushing coal trains around here.

Can you control Lionel engines as a lash up but split up in this manner? MTH? I don’t see why not but have not tried it.

Diesel and steam? N and W used to do steam with two in front and one in rear on steep grades. Now have to figure out how to control Jawn Henry (Sunset) with two Lionel.

Thanks.

Bill

Bill Webb

 

Old Hokie 70

One big advantage DP trains have, is that each consist has a feed valve, and can reduce brake pipe pressure to set the brakes on the train, at the same instant brakes are set with the lead engine. The brakes on a long train respond much faster than with a single feed valve on the lead consist. And, when brakes are released, they all begin to feed to the train line at the same time, quickly restoring brake pipe pressure,  and the brakes release just as quick as they would on a short train. Especially helpful in very cold temperatures on a long train.

locopilot750 posted:

One big advantage DP trains have, is that each consist has a feed valve, and can reduce brake pipe pressure to set the brakes on the train, at the same instant brakes are set with the lead engine. The brakes on a long train respond much faster than with a single feed valve on the lead consist. And, when brakes are released, they all begin to feed to the train line at the same time, quickly restoring brake pipe pressure,  and the brakes release just as quick as they would on a short train. Especially helpful in very cold temperatures on a long train.

There can be a problem with this. I discovered it when I ran radio trains back in the late 80's early 90's. If the combined feedvalves let too much air escape at one time, it can cause an undesired emergency brake application to occur. Hopefully, they have this problem taken care of by now

FWIW, this works with model trains as well.  When I was trying to do my 115 car pull on the club layout, I started out with the engines in front, but coupler issues kept biting us.  When I moved the second engine to the middle of the consist, we got things moving.  The amount of stress on the couplers of a real train with 100+ cars in trail must be astronomical!

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