In the November 1964 edition of Trains there is brief article about the L&N (Louisville & Nashville) using mid-train slave engines on a freight train. The slave engines had no contact with the head-end engines or any wayside stations - they used strain gauges on the engine couplers. The strain gauges were in turn connected to a computer, which then determined how much power to apply to the mid-train engines.
Were slave units a new idea in 1964, and is that approach still in use today?
Wow! That sounds “truly scary”. I’d appreciate any more info.
Here is a link to a site about L&N’s Appalachian Mountain Railroading and a quote about their “slave units.”
http://www.spikesys.com/Trains/App_coal/apcl_3a.html
"…The Ohio & Kentucky Railroad extended as far north as the Licking River before being closed during 1933. Pictures of the O&K are rare and the only one I’ve seen is in UK’s Special Collections Library of a derailment during the late 1920’s that shows a small steamer on it’s side. Today there is absolutely nothing left to be found of this small coal hauler. The L&N briefly played with remote controlled midtrain helpers or Remote Multiple Units (RMUs) on this grade during the period from 1968 to 1970 but gave up after several problems.
The L&N modified a total of four, Alco F2B’s as slave power cars to receive commands from four EMD SDP35’s equipped with radio transmitters. These train sets operated from the yard at Dent to Hazard, Ravenna, Winchester, and then north to terminate at DeCoursey, the huge classification and hump yard just south of Cincinnati. Two SD35’s up front with two more near the middle with the power car would take 200 loaded hoppers from Dent to Jackson where the two helpers were added on the rear to shove the entire set over Elkatawa Hill intact. Once at Ravenna, an additional 50 cars were added for the trip to DeCoursey. The return trip usually saw 300 empties run all the way back to Dent where mine runs distributed the hoppers at local mines while the RMU’s were serviced at Hazard. The RMU operations had been cursed with problems from the start, such as loss of control through tunnels, crew attitude and drawbar breakages. These long trains were run almost everyday until 1970 when Extra 1701 suffered a continuous series of drawbar failures that blocked the EK mainline for over 24 hours. Louisville became tir
The strain gauge method of remote control was tried on both L&N and SOU, it was judged a failure by both and quickly abandoned. The radio remote control was the first generation of Locotrol which was developed by a company called Radiation Inc. It experienced difficulty with radio transmission in the mountains and especially through tunnels. With improvements in radio technology and digital transmission through succeeding generations the Locotrol system evolved into the system now known as Distributed Power, along the way Radiation Inc. was bought by Harris Controls, which in turn was bought by GE.
One might wonder if today’s technology could make the concept workable. There is certainly nothing (that I know of) wrong with DP as it exists today, but I wonder whether a locomotive set up to maintain near zero buff/slack on the front coupler would allow what amounts to two or more trains (loco’s mid train) all coupled into one train. That would mean that the mid-train DP would not be pushing, but the power ahead of it would only be pulling those cars located ahead of the DP.
Today’s comms would still allow monitoring and control (as needed) of the DP locos.
I’m not holding my breath.
Last time I was at Tehachapi, seeing a mammoth UP manifest freight with 3 x ES44AC on the front and 3 x ES44AC mid-train grinding upgrade at 15mph or so does make you appreciate how effective modern DPU operation has become…27,000 HP and enough tractive effort to move a town…[8D]
Tony
Tony:
You could be correct, most likely the midgtrain units were most likely under control of the Head End Engineer. Union Pacific has the DPU system on many units and it is easily controled by the Engineer. Around here DPU is usually placed on the very rear of the trains, probably due to the flat nature of the terrain.
On Cajon, Tehachapi, and other heavy mountain grades the DPU’s can be placed in the most effective location in the train; according to the specifics of the railroad’s operational experience.
Mid-train placement location is dependant upon trailing tonnage restrictions on the most severe territory the train will cross, which is based upon grade and curvature. Trailing tonnage and curvature result in ‘string line’ type derailments where as the train is passing through curves, the trailing tonnage tries to pull the train in a straight line and thus derailing when the tonnage exceeds the wheel/flange/rails ability to keep the cars tracking around the curve.
Doesn’t UP use some GEs with “Variable”, or “Down-Rated” power for mid-train or DP EOT jobs?
The GE’s are ‘Controlled Tractive Effort’ equiped - in other words the control software makes sure they don’t push/pull quite as hard as the leading units so the train stays taut.
UP labels the units I watched as ‘C45AC-CTE’ where CTE = Controlled Tractive Effort.
Tony
The method of control may be new but midtrain helpers were used utilizing steam engines as numerous pictures exist. Most I have seen are N&W trains using steam engines so the idea has been around for over fifty years.
The method of DPU control goes back over 40 years and operating Steam locomotives midtrain was done well before WWII…