70000 Britannia

When the Britannias were built the axles were machined with a 1in500 taper as per LMS practice and the wheels, which had a parallel bore, pressed on. However, due to wheel movement on a number of locos, the first 25 locos of the Class were withdrawn from traffic until the cause of the problem was identified and rectified. Indeed, 70024 never even got out of Crewe Works.
It was decided that the wheelsets were to be modified with both the axles and the bores in the wheels being machined parallel. The bores were made with an interference fit of 0.010" on the axle diameter. The axles had a 3/4" long lead on them. The keys and keyways were also modified.
The problem appeared to have been solved until movements started re-occurring in 1958, 70013 being the first loco noted by Bill Harvey in his book.
It is hard to say how many locos this happened to, except for the locos allocated to the Eastern Region. On the loco record cards, Doncaster were very precise as to the reason a loco visited the works.

 

Could you please post a link? I've looked on Riley's website and despite a big blue 'in the works' in the middle of the page it seems to not work for me. Thanks in advance.

 

Try this:
http://intheworks.co.uk/forum/index.php

 

Many thanks.

 

I would have thought having the axle tapered and the bore of the wheel parallel to be a fatal mistake and something which is asking for trouble. The practice over here in Aus (well the locos I have worked on) was to have both the Wheel and Axle tapered (don't know the figure).

Some time ago (in AUS again) there were some Roller bearing fitted driving wheels that had their wheels pressed off (nearly 300tons needed) to have bearings replaced and axles shortened for conversion to Standard Gauge. Some photos and info here http://www.railpage.com.au/f-t11307547-0-asc-s200.htm (some photos not working)
When these Wheelsets were reassembled rather than pressing them back together the Axle was immersed in liquid nitrogen for about 1.5 hours to shrink them enough to go in the wheel, wheel & axle both being tapered about 1 in 120? is a figure that rings a bell. I was told at the time how much of an interference it was but cannot recall the exeact figure but it was alot more than .010".

 

Cant seem to check the images but presumably there is a Key as well ?

 

The Locomotive Manufacturers Association recommendations are for an interference fit of 0.001-2" per inch of diameter for steel wheels and 0.0005-15" per inch of diameter for cast iron wheels. Wheels should be machined parallel; axles can be parallel or tapered, that taper not to exceed 1 in 500 for steel wheels and 1 in 750 for cast iron wheels. Minimum pressing tonnage should be 8 tons/inch of axle diameter. (6 tons for cast iron.) As a point for discussion I would have thought that hollow axles would require a larger interference than solid axles although there is no comment on this in the LMA handbook.
Interested to know how the axles could be shortened as the roller bearing seats should have been larger than the axle diameter so there wouldn't be sufficient metal for the bearing seat. Surely, new axles required?

 

There was no need to replace Axle as this was a feature designed into the Loco when Built. The position of the bearings on the axle does not change each wheel ends up 3 1/4 inches closer to the bearings, the Wheels and axle machines tapered (unsure how much 1 in 120 rings a bell though.)

And to answer the earlier question they are keyed.

Some info here http://www.locomotiverestorationgroup.org/#!technical not limited to Wheels & axles of Victorian Railways Engineering practices.

 

Some interesting documents to read there when I get time. I did read the one on steel boilers. Amused that boilers had to be coated with Smudge. I never realised it was used on that scale. I haven't seen it available for many years, although I do have a very small tin in the garage.

 

There is a product called Apexia? which has been used in some Boilers but it's use is certainly not widespread and with Good Water Treatment is not Necessary.

 

Apexior is still available in the UK. It has always been recommended for painting the inside of Sentinel boilers (even BR did this) but, as you say, probably unnecessary with good water treatment. However, according to the VR instructions, the Smudge was use on the outside of the boilers. Today, we would usually use high temp. aluminium paint.
Back to pressing wheels on axles. I've looked up theBR (LMR) instructions for this and they are identical to those of the Locomotive Manufacturers Association. I think your recollection of 1 in 120 must be wrong. That is quite a steep angle and the wheel would almost slip on until the last few thou. (or mm!)

 

Last week 70000 undertook a 60mph test run on the MHR. Details on the new Ropley Shed blog:
http://preservation.watercressline.co.uk/blog/entry/the-times-they-are-achanging

 

Thanks for that Green Five. Good news indeed. This is the short piece of text regarding Britannia:

''As I departed at the end of the day, I noted a few people assembling on the station platform. The railway had received dispensation
for a 60mph test run of Britannia, and sure enough we were treated to the sight of it accelerating through the station''. <BJ>

 

Class 33 diesel locos has parallel axle seatings and wheel bores, with an interference fit of 0.00088888" per inch of diameter. Or 8 thou for a 9" diameter axle. Pressing tonnage of 11 - 13 tons per inch of diameter of wheel seat.

I have no idea of the different characteristics of spoked and disc wheels.......

 

Britannia is off back to Southall tomorrow from Alton, departing 09.21 via Willesden:

http://www.realtimetrains.co.uk/train/U53012/2015/02/27/advanced

 

Next booked trip is the Great Britain VIII


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A freshly painted 70000 unveiled today at Crewe:

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Well, to all at Icons of Steam, VERY well done and thank you.
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Now let's have it up the S&C.
I'll have 2 tickets.....table for 2, first class.

 

Premier Dining of course

 

Sprouts and vindaloo☺