Quote:
Originally Posted by Master Cutler
A question mainly for the drivers/ex-drivers regarding the winter months.
There are loads of "clag" videos of Diesel cold starts where locomotives need to be warm before moving off.
My question relates to the electrics, what warm up if any does an electric locomotive need, during say sub zero weather, before it can move off?
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AussieSteve is the loco man, so I'm sure he'll give you more detail on those than I can as I drove EMUs, but I'll stick my 2p in anyway.
I believe the big issue is whether the unit in question has been sitting on the juice all night, or whether it's been cut out. If it's the former, then it should be warm and full of air - so pretty much ready to go. Certainly a modern one. I'm told however that on some of the older Slam Door dc EMUs of the Southern/South Eastern, the air compressor didn't run if the driver's key was not in the desk (which it shouldn't be if the unit is unattended), so you would have to wait for the air to pump up before you moved it. About a 10 minute delay if all worked properly. Also these old units had a manual parking brake. It was located on thd 2nd man's side of the cab and looked like a ship's steering wheel (some passenger's have actually asked me "why does that thing have a steering wheel, you guys don't actually steer do you?") . I mention this because in really freezing weather the parking brake could have frozen on. In which case, time to call the fitters out.
In the second case, where a traction unit has been cut out overnight, things can be a real pain. If you remember your schoolboy chemistry, the speed of a chemical reaction is proportional to the temperature. A battery is just a big heavy bucket of chemistry, which handily can produce electric current. On a stinking cold day it just doesn't want to do its magic. We need the battery to get our unit connected to the juice. Firstly to close the massive Master Circuit Braker, and secondly to either lower the dc shoes or raise the ac pantographs. This is done by air, so we need the batteries to operate the compressors. That's a big ask, and often it doesn't happen - so fortunately there's a Plan B and a Plan C. Plan B is that often there is an "auxilliary compressor" located in a dark corner. We can go to it and manually toggle it to run. This is a little low-power device which doesn't feed air to all the big brake reservoirs or other systems, ONLY the pantographs or shoes, just to get the unit on the juice. Plan C is Thunderbird Rescue time. Hopefully somewhere nearby is a unit that is still running on the juice. We'll hook it up to our unit and pass air through their Main Res Pipe to ours, so we can get our pans up / shoes down .
Sounds great, but often we are subjected to overnight isolations, where a whole area has the juice switched off to allow linemen to work on the power supply. In this case there isn't a unit anywhere to provide donor air. In which case all the drivers and shunters retire to the lovely warm messroom, whilst a poor Fitter drives 50 miles through ice and snow to come and rescue us. Usually when they phone to say they're on their way they're told, "Take your time mate and drive safely, we've got a card school to finish here."
Cheers, John