71000 Matters

I suspect it's just that what we're used to seeing looks normal and what we're not used to seeing looks odd.

 

E S Cox mentions that it was intended that the standards should have had outside roller bearings everywhere apart from driven,but it got in conflict with the UK loading gauge.

 

And yet the Kings have outside bearings on the front axle.

 

But weren't they restricted to previous broad gauge routes where the kinetic envelope allowed it ?

 

Don't think so. AFAIK the King limits were purely on weight limits/bridge strength. Very complicated subject because under platform height its all very critical. Above platform height it was sometimes *slightly* more tolerant because the very occasional coach door handle being knocked off wasn't a disaster. On the other hand, any lateral movement is magnified the higher above rail level you go.
Something that amused when I was studying the subject at Kew was an LNER proposal for a properly planned and designed composite gauge, incorporating safe allowances for dynamic movement etc, which was rejected by the running department because it would have banned certain stock from routes it had been running on for many years.

 

Complete news and very interesting. Was said proposal made in respect of LNE lines, or to start a move towards a uniform UK envelope?

 

It was just LNER. They did, I think, move to a composite loading gauge, but I didn't find a drawing/dimensions. I *think * it was RAIL 396/11.

 

Thanks Jim. I was aware of a Southern 'composite' loading gauge, not including Hastings, the Canterbury & Whitstable of Isle of Wight lines and (vaguely aware of) the BR era 'L1' standard, but only thanks to Mr Riddles' tweaks to Mr. Fairburn's Class 4 tank locos to make the BR version fit more lines.

 

Does anyone know what the plan for the Duke’s operations will be post overhaul? Will it be run in at the SVR?

 

The reason for which no-one has ever satisfactorily explained to me.

 

Will it be run in, I know its under a separate banner, but Tyseley overhauls normally just do a few runs to Stratford don't they?

 

I understand that it was to provide sufficient clearance below the inside cylinders. The LMS Lizzies had their cylinders in the same location but used inside bearings. On the other hand, the King bogie was a plate frame while the Lizzies used bar frames.

 

I thought it was to allow the bogie sufficient swing while clearing the inside cylinders, which are larger on a King - the front axleboxes on a conventional bogie would foul the (bigger) cylinders otherwise.

Tom

 

You are right Tom. There was also a lot of trouble with the springs resulting in a derailment ash Midgham in 1927 and there was more trouble with the bogie frames in the 50s. One bogie on 6004 was modified with a slotted front stay, presumably to increase airflow around the bogie axle boxes. It was moved around on overhaul and was recorded on 6023, 6018,6028, 6014, 6024 6005 and 6021 in that order ( source, The Book of the Kings, Irwell Press)

 

Did the LMS engines have horizontal or inclined cylinders? If inclined, it would have slightly raised the cylinders and given the bogie a little more space than on the GW Kings with their horizontal cylinders.

 

Good point. Would be interesting to see if it works solely for Vintage Trains or ends up working with others such as DBC. I must say I was surprised not to hear 71000 mentioned in the Steam Railway Magazine article about Tornado as 71000 was solely DBC operated when it last ran.

 

The outside cylinders were inclined but the insides were horizontal.

 

I just found this on RMWeb, courtesy of "Miss Prism"... Interesting.

The expensive insistence on using 6'6" wheels for the Kings, in order to achieve the prestigious 40k lbs tractive, led to the 'cylinder line' on the Kings being lower than that of the other big-wheel 4-6-0s, and it was found difficult to squeeze the existing Churchward barframe design in. This, and the desire to go to a plate frame design because of perceived (rivet) weaknesses in the Churchward barframe, led to the half-outside half-inside format for the King bogie. In the event, the weaknesses in the barframe structure was discovered subsequently to have arisen more from the lack of diagonal bracing rather than rivet cracking. Had this been known at the King design stage, they would probably have had a version of the Churchward barframe bogie.

And this from "The Johnster"...

It is a consequence of the divided drive de Glehn 4 cylinder layout inherited from the Stars and Castles and the 6'6" non standard driving wheel of the King design. The smaller driving wheels allowed a larger boiler to be squeezed into the loading gauge but it had to sit at a lower centre line, which meant that the bottoms of the inside cylinders, set forward to drive the leading axle, came perilously close to the top of the leading bogie, which had to be allowed room to bounce around a bit at speed. This then required the front of the bogie frame to be outside the wheels to allow the frame to rise around the bottom of the inside cylinders, especially if the loco was dipping forward under braking at speed and sitting down on the front springs, the rear wheels of the bogie being inside framed as this axle is to the rear of the cylinder casting and the motion does not get in the way; there's plenty clearance there.
Plus it gave a nice brass outside bearing to be polished up; the GW liked a bit of polished brass on it's locos...

Richard.

 

Thanks for those explanations of the King bogie. I now understand why the Princesses didn't need the same arrangement.