BR HD DMU passenger window frames

[Chris Higgs]

I'm trying to get information on which High Density DMUs had aluminium window frames and how they originated. By looking at photos it seems that all classes had the passenger windows held in by a rubber seal, except for Class 121 and Class 115 - although perhaps not all of these - which had a more prominent aluminium window frame, similar to the frame fitted to later BR Mk1 coaches.

 

Here's a photo of a 121 with window frames

 

http://en.wikipedia.org/wiki/File:960011_At_NRM_York.jpg

 

and a class 122 without

 

http://en.wikipedia.org/wiki/File:55006_at_Bewdley.JPG

 

Can anyone tell me whether my analysis is correct, and if the Class 121 and 115 were built with these frames, or if they were added later.

[dibber25]

Looks like it was the standard Pressed Steel construction method (117s certainly had the frames when in original green). All my early PS Single unit photos are at home, so I'll check tonight and see if I can scan and post a couple of examples.

CHRIS LEIGH

[dibber25]

Yes, is the answer, Pressed Steel units had the 'framed' windows from new. This is W55027 at Twyford on the Henley branch service. The frame on the leading side window is particularly clear. I also have a black & white shot of a Pressed Steel DTS in about 1963 which clearly shows the 'frames'.

Notice the flaking paint on the windscreen frames - a sure sign that they are aluminium.

Also note that the code on the end is MBS. This was normal at the time, the 'D' (for driving) generally being used only with trailer vehicles. It was much later that they became DMBS. A current article on the codes fails to mention this. Also, it is worth noting that, while the current code for a diesel railbus is DRB, the vehicles originally carried the designation SO (second open).

CHRIS LEIGH

[Chris Higgs]

Thanks for this info Chris.

 

By examining various photos of Class 115 DMUs I think I heve deduced what happened with this class. Although built at Derby, the final batch (e.g. power cars M51861-900) also have window frames like the Pressed Steel units. The first two batches (M51651-80 and M51849-60) did not.

[roythebus]

Window frame technology has advanced over the years. Whilst I can't be specific about the unit in question, in my other life a a bus restorer, I see dozens of different methods of fixing windows! There's a company that supplies rubber strip to hold windows in place and they list well over 1,000 different sections!

 

If you're interested, just have a look next time you get on a bus or train. You'll find side windows are now bonded to the metal panelwork, with front and rear screens held in by rubber for ease of replacement, while some side windows are held in by rubber!

 

I suspect with the DMU builders, they used what was on the market at the time.

[RANGERS]

Window frame technology has advanced over the years. Whilst I can't be specific about the unit in question, in my other life a a bus restorer, I see dozens of different methods of fixing windows! There's a company that supplies rubber strip to hold windows in place and they list well over 1,000 different sections!

 

If you're interested, just have a look next time you get on a bus or train. You'll find side windows are now bonded to the metal panelwork, with front and rear screens held in by rubber for ease of replacement, while some side windows are held in by rubber!

 

I suspect with the DMU builders, they used what was on the market at the time.

 

Not always the case, most manufacturers still offer bonded or gasket glazing on service buses, many operators (Arriva and Stagecoach to name two) specify gasket glass throughout for ease of replacement. Some models don't offer gasket glass as the glazing contributes to the structural rigidity of the vehicle, the Optare Solo falls into this category. Even with modern adhesives, it's recommended a vehicle is left untouched for 12 hours after a new window is bonded into place, a big disadvantage when a gasket glazed window can be replaced in about half an hour.

 

Coaches are generally bonded glass, even on front screens on more modern designs, and most rely on this as an element of structural strengthening to maintain rigidity around the front end. This allows much larger areas of glass to the front end as on the Jonckheere SHV and Plaxton Elite.