Project Wareham

Whilst we're totally OT, the so-called metric standard for nuts and bolts is even better. UK, Germany, Japan and the USA all use different A/F sizes for their nuts so you need 14, 15, 16 & 17 mm spanners for M10 nuts and 17, 18 & 19 mm spanners for M12. Japan even uses a different pitch (1.25mm) for its M10's. Beware!

 

What do the owners of the many heritage DMU's around the country do about wheelsets and measurements? This problem seems to have come as a surprise to SR but, some of these other groups must have had to deal with this before now. Isn't there any communication between DMU owners nationwide?

 

Good Point..............

 

Considering that completely new wheelsets have been needed, and made, for some of the new build projects (and for Britannia?), why is sourcing replacements for a DMU so complicated, involving suppliers in three different countries? Regardless of what system of units is in use, can't parts be machined to whatever sizes are needed?

 

I suspect retaining the grandfather rights of the class 117 is what causes the issue here. Roller bearings are basically sold as off-the-shelf units by the suppliers, you make no alterations to them or you'll lose all certification from the supplier that it takes the load and provides the service life claimed for it. So if you can't can't get the right size and you can't change the bearings, you need to change the axle or housing. Well suddenly that's not a 117 any more, it's a variant on the 117 design, and somebody will have to provide suitable evidence that the modified design is fit for purpose (calculations, experiments, whatever). That can be a lot more expensive and time consuming than obtaining the correct bearings, so if it's at all possible to obtain bearings of a suitable size and rating then that's the sensible thing to do.

 

I suspect that the standard that is alllowed on the main line is of a greater and higher spec than that on preserved railways

 

We did look into altering the sizes of the axle bearing journal and axlebox bore to suit metric bearings. But as stated above, any deviation from original design needs to be backed up by worked calculations of stresses involved. There are only a small handful of engineering consultants with the relevant competencies and approvals for doing this work.
All told, it would have cost more than the price of the new USA made bearings and taken nearly as long to produce the calculations as waiting for the new USA bearings. And then finding a contractor to spiral weld and machine the axleboxes would have added even more time and expense.

 

Not really, ROGS applies to everyone. You couldn't (well ok, shouldn't because I realise some railways have in the past probably done so) make an alteration of the type described above without the approval of an independent competent person. You may not have to apply as stringent an engineering standard to the parts since the speed will be lower on the heritage line, but the general process and the requirement to be able to demonstrate that you have calculated the effects is the same.

 

If you look closely at some of the CAV fuel injection pumps on the DMUs you will find metric threads with imperial spanner flats!

 

AARGH!!!!!!!!!!!!

 

Which is why I'm right in my opinion that the world should have standardised upon imperial measurements and in particular thread sizes:-
BSW for general use
BSF for high tension applications
BA for sizes smaller than 1/4"
BSP for pipes

All those Bs for British may appear jingoistic but they were invented here!

 

Why should we have standardised on imperial? The rest of the work (apart from the Americans) have all standardised with metricbecause it is a much better system just 10's 100's 1000's etc. It is a lot easier for children to learn and because , for example, 1cm3 is 1 ml it means you can easily change the units. I think the UK should go over to entirely metric not the the strange half and half we have today. Plus thinking bearings for a first generation DMU would be off the shelf is simply delusional.

 

Have to disagree, having worked on Metric, American and British threads worldwide on equipment designed and built worldwide the simpler metric threads are generally far better . For design SI is also streets ahead of Imperial. Just try developing a few designs in heat and mass transfer, fluid or thermodynamics in imperial and then SI and the penny will soon drop as to why the imperial system was doomed when the Empire went.

I suspect this is a subject on which entrenched views are held which no amount of logic will shift.

Brian

 

How far is it from Wareham to Swanage by rail? And how far is on Network Rail?

 

Just over 10 miles with about 1 mile on NR .....give or take a few chain

 

Adam - your simplistiv view is fine for new build and it is what you will find in manufacturing. What we have in the heritage world is to the standards of the day when the vehicle was built. You can use metric bolts in some situations which are not safety critical. However if you have a major casting which has holes for studs threaded 3/4 whitworthyou have to use 3/4 whitworth studs. Similarly if you have two expensive to replace components drilled for 1/4 whitwirth the metric equivalents are either too loose or too tight. only a 1/4 in bolt will work. I have a 1976 Landrover and can categorically state if a hole needs a 1/4 inch bolt then you use a 1/4 bolt

 

I'd like to get journalists to stop saying that a building is 10m high, covers 5,000 sq ft on a site as big as 4 football pitches!

 

I must admit that having been to Australia & New Zealand, I had to admire that they had just got on with going metric & not faffed about with it in the way we have. Ironically of course since the late 19th Century the Imperial measures were standardised against metric ones........

Clearly in the 'heritage' world we will have to live with Imperial - Oh & don't forget those poor souls at Crofton whose threads, bolt heads etc long predate Mr Whitworth et al

 

It's culture John. In Australia, New Zealand and especially Ireland, the public mood was to kick imperialism into the dustbin. In Canada, the changeover was great for uniting English and French speakers whilst simultaneously making the whole country different from the US.

 

I believe a similar expedient was adopted in engines for the bullnose Morris Cowley!

PH