Diesel Loco question from new member
 

Hello,

I'm new to these forums and must confess to knowing very little about trains in general despite holding a strong interest in them, however I do have one question that i'm sure can be easily answered.

Last night whilst waiting for my train to pull out, we were sitting next to a set of carriages with a diesel locomotive at each end. I've often wondered, how are the two diesels connected so as the control inputs from the front loco is repeated in the second?

Fraser.

Hello fraser and welcome, I have no idea but You will get an answer soon.

Hi Fraser.

I think that the control is effected using circuits through each coach of the train. Connected one to the other until the second loco is reached.

As far as I am aware this is called something like multiplex control using standard inter coach connections. I wonder if in this particular event both locos were working. I think has been known for a loco to be returned to a remote depot "dead" in/on a train. Of course this operation is standard practice with HST 125s.

In push/pull trains there is a system called TDM (Time Division Multiplexing) which enables the control signal between the remote driving trailer and the actual locomotive to be passed through the lighting circuit cables of the intermediate coaches.
I don't know if this also applies to locos at either end of a train.
John.

That's what I was trying to think of.....honest! :D

TDM certainly is used in push pull, but I am not sure whether it is the system used in HSTs - I think that TDM post-dates the HST. ON the old push pull sets used for Glasgow Edinburgh (with Class 27s - anyone remember?) the wiring was bespoke. Not sure how it is done these days - most use lead loco under power with the trailing loco providing other sources such as ETS or additional braking power...

Hope that helps

on a HST there is usualy a set coach set to go with the power cars, and basiclay when the coach set is coupled with the power car, there is a wire that transmits info from one power car to the other so that if one setting is changed in one power car, the trailig power cars speed or brake apliance so on changes to

most of the time with 1st generation diesels the rear loco is hauled as an additional vehicle the driver, depending on type, has to isolate the DSD on the rear etc.... 'top and tailing' is done nowadays to save money on running round the train or maybe the train traverses a branch with no run round facilities.....TDM was/is used on the overhead electric hauled services and is a little different to remotely controlling a loco from another loco....

Yes, I remember them very well indeed. In fact, the only bespoke parts of the trains were the uprated disc brakes fitted to the 27/1s and 27/2s, and the ETH (ETS/HEP) fitted to the 27/2 subclass. <edit - disc brakes on the Mark 2 coaches too>

Most people are surprised when they find out the the coaches were fitted with standard blue star multiple working cables throughout so the locos thought they were next to each other and were working in multiple. I don't know if there are any photos existing but if there weren't enough 27/1 or 27/2s available then 37s used to deputise and you would often see a standard class 37 at one end although I can't recall seeing the service ever with a 37 at both ends

Seen at Wansford this morning
 

I personally have no idea what class or anything like that it might have been but I'm sure someone will know. Ex BR? number 14029 in blue (and no rust) plate on side with Ripple Lane and beneath RL in big letters I assume to be a shed or depot and built Swindon 1965. It was being unloaded from a road transporter from Reid Transport. The artic trailer was interesting as it has been modified to transport rail stock and the front end over the turntable had what effectively were grooves in the deck that more or less matched up with the rails fixed along the remaining length of the trailer, this section was about 10 feet or so long. The rails themselves were fixed to the trailer with bolts and supported by sleepers. Assorted lengths of rail were also on the trailer ready to use to connect with ground level track.
When we first saw the loco on the transporter they were shunting around getting it lined up with the tracks after which the tractor unit was removed and the front of the trailer lowered to the ground. We could not stay until the loco was being unloaded but as we left they were building up with sleepers before connecting the rails so that the loco could be tun off onto the track.
Next weekend is their Diesel Gala so whether this was a visitor or a 'new' loco being delivered. I did find out from one of the Reid people thast the company does do a lot of railway transport and have longer trailers modified with these 'rail sections' built into the front end of the trailers for use when transporting larger locos.
Maybe we will get there and see something next week.
John
PS Is there a spell check anywhere we can use?

John, It is a class 14 diesel-hydraulic affectionally known as a "Teddy Bear"
Apparently this particular loco is based on the Nene Valley.
Details here
John.

Hi John,
Thanks for the information so if it is normally resident at Wansford it must have been out somewhere. While we were there we heard a steam whistle but saw nothing running but on the wasy home we did see some steam so perhaps there was some filming being done today.
John (10 mins south of Wansford)

And the number 14029 is ficticious. None of the class survived long enough in BR service to be renumbered under TOPS. The original numbers began with 95.