RMweb Gold TheSignalEngineer Posted January 8, 2018 RMweb Gold Share Posted January 8, 2018 As Bachmann haven't announced a 74xx variation of the 64xx Pannier, I decided to bite the bullet and start the conversion I have had sitting waiting on the bench. Whereas the cab roof and bunker is quite straightforward I have a question about the chassis. I can live with the fact that there was a variation in the brake gear, I don't think it will be noticeable when running on the layout. Under the driver's side of the 64xx behind the steps there is a double box which I thought was the ATC battery and control box. I had been under the impression that the 74xx series were built without ATC and it was only fitted to a few on lines like the Fairford branch. Pictures of the driver's side seem to be a bit thin on the ground and those I have are lacking in detail at that level. However, quite a few have the box visible, so what was it and did they all carry it? Link to post Share on other sites More sharing options...
Miss Prism Posted January 8, 2018 Share Posted January 8, 2018 Only a few 74xx are thought to have been fitted with ATC, all working the Fairford branch at some time or other (7404, 7411, 7412, 7417, 7436, 7445). Those fitted with ATC would have had the battery box, positioned as you described (tucked away, 'half and half' as it were, behind the driver's side step). Link to post Share on other sites More sharing options...
RMweb Gold TheSignalEngineer Posted January 8, 2018 Author RMweb Gold Share Posted January 8, 2018 (edited) Thanks Miss P. Good pictures of the driver's side seem few and far between, but I'll keep looking to match probably one of those at Stourbridge Jn around 1960. I've found shots today of 7403/4/23/27/45 with boxes and 7428 without. Edit: Shot of 27 without box in 1956, so jury out on that one. Edited January 13, 2018 by TheSignalEngineer Link to post Share on other sites More sharing options...
Miss Prism Posted January 8, 2018 Share Posted January 8, 2018 I've found shots today of 7403/4/23/27/45 with boxes Interesting - more than I expected. Perhaps there was a late flurry of ATC fitting on the 74xxs. Link to post Share on other sites More sharing options...
RMweb Gold TheSignalEngineer Posted January 9, 2018 Author RMweb Gold Share Posted January 9, 2018 Interesting - more than I expected. Perhaps there was a late flurry of ATC fitting on the 74xxs. I'll post up a list of what I've found when I've been through them all. 1 Link to post Share on other sites More sharing options...
RMweb Gold TheSignalEngineer Posted January 13, 2018 Author RMweb Gold Share Posted January 13, 2018 Think I have spotted another give-away. The 54xx and 64xx all have a conduit from the ATC box which goes across the top of the driver's side step and up into the cab. This is only present on some 74xx so it helps with the ones where the box isn't visible. I feel a chart coming on. It's easier to see the box on a 54xx and 64xx because auto fitted locos have two side by side, whereas the ATC fitted 74xx only has one box next to the sandbox. Link to post Share on other sites More sharing options...
Miss Prism Posted January 14, 2018 Share Posted January 14, 2018 It's easier to see the box on a 54xx and 64xx because auto fitted locos have two side by side, whereas the ATC fitted 74xx only has one box next to the sandbox. Why? Link to post Share on other sites More sharing options...
RMweb Gold TheSignalEngineer Posted January 14, 2018 Author RMweb Gold Share Posted January 14, 2018 Why? I assume the second box was for the Autocoach Bell Battery. The 14xx also had two boxes, 58xx had one. ATC-fitted panniers in the 57xx/8750 and 94xx had a single box in the same position as the 74xx. On 15xx it was directly below the middle of the bunker. I haven't found a picture of a fitted 16xx yet. Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted January 14, 2018 RMweb Gold Share Posted January 14, 2018 The 'other' box was indeed for the auto trailer bell battery (there was bell communication between the driver in the trailer cab and the fireman on the loco). It is also a giveaway to an auto-fitted 4575 from that angle. Link to post Share on other sites More sharing options...
RMweb Gold TheSignalEngineer Posted January 14, 2018 Author RMweb Gold Share Posted January 14, 2018 I've just noticed that BR livery versions of the Hattons/DJM 58xx 0-4-2T have the twin box of auto-fitted locos when they should have a single box. Did anyone spot this at the time they came out? Link to post Share on other sites More sharing options...
Miss Prism Posted January 14, 2018 Share Posted January 14, 2018 Hmmm, I wonder if the 'second box' provision is to provide for gas-lit autocoaches that didn't have their own batteries? 1 Link to post Share on other sites More sharing options...
Miss Prism Posted January 20, 2018 Share Posted January 20, 2018 All this has got me wondering how pre-1930 locos powered their ATCs. Link to post Share on other sites More sharing options...
K14 Posted January 20, 2018 Share Posted January 20, 2018 Hmmm, I wonder if the 'second box' provision is to provide for gas-lit autocoaches that didn't have their own batteries? Not just gas-lit trailers. The ATC system ran on a 4 volt system, whereas the carriage electric lighting circuits were all 24 volt. Putting a pair of boxes on an auto-fitted loco makes a lot of sense to me as then both sets of cells would be changed at the same time & remove any doubts as to the state of the cells if they were carried somewhere in the coach. All this has got me wondering how pre-1930 locos powered their ATCs. Still on 4 volt batteries. According to Wikipedia, lead-acid cells 1859, wet cells 1866, dry cells 1886 & NiCd 1899, so by 1909 they'd had 50 years of development. This does pose two further questions… How often were ATC batteries changed — daily? weekly? Where were they re-charged? Works? Large shed like OOC? Didcot doesn't have a side room marked 'Accumulators' within the shed, so presumably there were central servicing & distribution points and subsequently traffic. A bit of further reading on ATC, for those so inclined, in the form of two Swindon Engineering Society lectures:— "Automatic Cab Signalling" by H. Arkell, March 2nd 1909:— P_091.PDF "The Automatic Train Control System of the GWR" by A.W.J. Dymond, March 10th 1936:— P_206.pdf Pete S. Link to post Share on other sites More sharing options...
RMweb Gold TheSignalEngineer Posted January 20, 2018 Author RMweb Gold Share Posted January 20, 2018 (edited) All this has got me wondering how pre-1930 locos powered their ATCs. According to one of the papers referenced they were originally dry cells but on the diagram these had been replaced by NiFe cells. These came in wooden crates usually of 1,3 or 5 depending on the use and capacity required. In the early days the batteries had to be changed every 14-21 days. They weren't on all of the time as the circuit was controlled at one time by a pressure switch which detected the boiler pressure later by a switch worked off the vacuum reservoir on the loco, so that the battery was switched off automatically when the loco was not in use. Edited January 20, 2018 by TheSignalEngineer Link to post Share on other sites More sharing options...
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