Buffered up

[Pete the Elaner]

On 02/03/2020 at 20:53, rab said:

Interesting, is the reason for oval buffers that longer stock

led to more sideways movement of the buffers?

On that point, the first 2 Princess Royals, 6200 & 6201 first appeared with round buffers.

These locos were much longer than any loco previously built by LMS & their buffers were soon replaced with oval ones.

[The Johnster]

Interesting, especially as the Fowler 2-6-4 tanks, (and their LMS and BR successors) were built with oval buffers, as I believe were the big Furness and GSW Baltic tanks, so the LMS was well aware that long locos needed oval buffers.  Seems an embarrassing sort of oversight for such a high profile class...

[melmerby]

Looking at Russell's Southern locos most are 3' 5" with some at 3' 5½" but the A1X Terriers as 3' 6¼"

LNER looks like it was 3' 5¾", at least on some carriages. Some Midland wagons were 3' 4"

 

So much for a standard!

With such variation a "standard" gauge is pretty pointless.

[101]

2 hours ago, melmerby said:

Looking at Russell's Southern locos most are 3' 5" with some at 3' 5½" but the A1X Terriers as 3' 6¼"

LNER looks like it was 3' 5¾", at least on some carriages. Some Midland wagons were 3' 4"

 

So much for a standard!

With such variation a "standard" gauge is pretty pointless.

 

But what everyone is talking about is one figure, are these measurements from official drawings or from measurements someone has taken from a particular vehicle? - there will always be a difference in buffer heights due to loading and/or tyre wear (and suspension wear), but as long as the difference remains in the allowable range between max/min, which as I stated earlier in the thread, in my time on the railway was (basically*) 3'6" to 3'1", then things are ok

 

*Different classes of vehicles had different allowable ranges but all within the  3'6" - 3'1"

 

Edited March 8, 2020 by 101

[Nick Holliday]

18 hours ago, The Johnster said:

Interesting, especially as the Fowler 2-6-4 tanks, (and their LMS and BR successors) were built with oval buffers, as I believe were the big Furness and GSW Baltic tanks, so the LMS was well aware that long locos needed oval buffers.  Seems an embarrassing sort of oversight for such a high profile class...

Since the Princess Royals would do very little work tender first it hardly seems a problem, it's the tender buffers that are critical, so was the overhang greater than normal?

15 hours ago, 101 said:

 

But what everyone is talking about is one figure, are these measurements from official drawings or from measurements someone has taken from a particular vehicle? - there will always be a difference in buffer heights due to loading and/or tyre wear (and suspension wear), but as long as the difference remains in the allowable range between max/min, which as I stated earlier in the thread, in my time on the railway was (basically*) 3'6" to 3'1", then things are ok

 

*Different classes of vehicles had different allowable ranges but all within the  3'6" - 3'1"

 

Already noted. In general I have quoted dimensions off actual company drawings, as it is possible that "modellers'" drawings might just have assumed a figure of 3'6" was the standard, without checking with the prototype. It's interesting I've found a Barry Railway company drawing that actually specifies the 3' 6" buffer dimension is for an unloaded wagon, which is probably implicit in all cases.

Also in Snowdon's book on the Metropilitan he has reproduced a drawing for motor cars that gives heights "unloaded" and "unloaded" which are one inch different. Given that a motor coach might weigh 36 tons (an LSWR example) and the passenger loading would be only 10 tons maximum (100 passengers at 14 stone each) the loaded weight would be only 30% greater than the tare weight, whereas a goods wagon might have a tare of 6 tons and be capable of carrying 12 tons, so the total weight would be 300% of the empty weight, the commensurate compression would probably be several inches, but still, hopefully, within 101's range.

[The Johnster]

36 minutes ago, Nick Holliday said:

Since the Princess Royals would do very little work tender first it hardly seems a problem, it's the tender buffers that are critical, so was the overhang greater than normal?

Presumably so; the Princess Royals were probably the longest rigid framed tender loco in the UK since the Great Bear.  And it's not just a matter of tender first work, though that has to be possible if required in an emergency; the locos had to buffer up to others in shed yards, sometimes on curved roads. and be moved dead around the shed by a pilot loco, and may have been involved in double heading operations in service; Princess Anne piloted by Windward Islands at Harrow and Wealdstone comes to mind.  The tenders of course had normal buffers, as did the loco end of all other British pacifics except the Coronations.

 

The locos had to be capable of operating in any normal conditions, and it was clearly realised before the 3rd was in service that oval buffers would be needed at the front.  The LMS pacifics were much longer than the East Coast locos, longer fixed wheelbases and the wheels were individually further apart.  The LNER locos' driving wheels were very close together, less than an inch apart.