P2 Locomotive Company and related matters

I’m not sure I ever saw an unequivocal cause published. There was talk of oil quality, mechanical lubricator issues (number of pawls on the drive) and also lubrication of the actual valve gear (oil vs grease). I’d welcome any enlightenment.

 

It was fair enough that they took some time to work out exactly what had happened, but The Tornado Telegraph No. 93, from May 2018, said "On conclusion of the investigation we will publish an update on the key findings." Have we ever seen that?

As I recall, they did identify several (three?) factors that had caused the valve to seize, one of which was tolerances making the valve head a bit too tight, and they said that any one of those factors alone would not have caused the failure. They did say that speed was not the cause: it just caused the failure to happen a bit sooner than it would have done at a lower speed. Given that, and the original design intention of regular 90 mph operation to fit in better on the modern railway, it remains unexplained why they seem to have abandoned that intention.

Edit: I half remembered and have now found a bit more. See page 7 of The Communication Cord 51, downloadable from https://www.a1steam.com/tornado/new...egoryid/4/categoryname/the-communication-cord

 

I can see at least one practical, rather than technical, reason not to do so. If you promote a tour which can only be run to time if the loco can run at speeds up to 90mph, then you need at least two such locos capable of doing so - otherwise from the promoter's point of view, you are only one unexpected failure away from not being able to run your planned trip.

It becomes a bit chicken and egg: in the absence of a pool of 90mph-capable locos, as a promoter I'd be wary about promoting any trips that require that level of performance. But in the absence of any trips that require it, why would any other loco owner go to the expense and effort of obtaining permission to run at that speed?

Tom

 

That makes sense, although it would not be the only situation where a trip changes because of the unavailability of the intended loco. And it prompts the question why they originally intended 90 mph operation.

 

90 mph gives more options on the modern railway.

 

But iirc the 'exemption to run upto 90mph has not been revoked ( or does it expire with the 'ticket' and have to be regularly applied for) and so planned or not the loco could still be run above 75 if circumstances require.
I asked (DE grhs) about top speed for P2 and whether a max speed increase would be applied for... but based on wheel diameter and other factors a max speed of 80+mph might be considered subject to test, but the test procedures were such that it was considered not worth the effort for 5mph and that the P2s qualities of adhesion and acceleration were its strengths. Would imagine that with its long wheel base, new pony truck arrangement and Valve gear that POW will be both free running and stable at high speeds a '9f on steroids'... we shall see.

Did i also recall that the max speed permitted for steam locos was re examined recently and new speed limits applied to individual types based on parameters other than wheel diameter ( age, design purpose cylinder layouts etc) which benefitted black fives, with other locos (sir lamiel iirc) being slowed. Always considered 1 mph/ inch of driver diameter to be the most obvious 'Yardstick' to apply

 

Another factor is for some unfathomable reason ORR don't permit Mk1s to be steam hauled above 75mph, so the stock needs to be Mk2s or 3s. 100mph with a diesel or electric is fine though, and 60163 has done 100mph with Mk2s. So it's not down to the loco, the stock, the crew or the route that they've put that bizarre restriction in place.

 

Given that Bittern did her 90mph runs with nothing but Mk1s, that can be exempted if needs be.

 

That was several years earlier though. The ORR were certainly being blamed for Mk2s being required on the Ebor Flyer. The current Regulation 4 exemption states -

"(d) The operator must ensure that the Rolling Stock shall not operate: (i) at a speed in excess of 75 mph (120 kph) for steam operations; or (ii) at a speed exceeding the plated speed of the coach for electric or diesel operations."

I suppose an exemption to the exemption is possible.

 

This ia another point I have wondered about - in particular in connection with the new build 47xx, the large boilered GWR 2-8-0, 5ft 8in driving wheels - is could the speed limit be raised with balancing on modern principles and general stability checked on the same established computer programme as was used for the P2?

The balancing is more important than the wheel diameter: a 9f with 60 inch driving wheels at 9o mph has a ratio of one and a half times diameter to speed. No concerns over the effects of the revs on the track seem to have surfaced. But there were immediate concerns over the possible effects on the engines and a general speed limit for all steam locos of as many mph as the wheel diameter in inches was proposed, however, protests that this would preclude time recovery when engines were recurrently running into the nineties without evident problem effects were heeded.

 

Has anyone ever found a sound reason for that, or was it an unintended consequence of (a) the need for an exemption from some requirements to allow MkIs to run on the main line at all and (b) the presumption that when they do so behind steam the loco will be limited to 75 mph?

 

AIUI, the ban on Mk1's was for early 'plain bearing' bogies. Roller bearing 'Commonwealth' and later versions were permitted at 100mph.
Examples include the Mk1 BGs, newspaper vans and Catering vehicles which ran happily at 100mph behind electric traction in the Mk3 rakes.

 

Would it be wrong to infer that improved bogies - Commonwealth and as later developed - should clear Mark BR carriages for running now for 100 mph?
There may even be some surviving ones that qualify on "grandfather rights" in their own right having been cleared for and run at that speed.

Are roller bearings rather than plain ones ones crucial?
They are now for freight cars in the USA, certainly to travel off their own lines, AMTRAK also insisted on them if they hooked on a private passenger car to their trains.

 

I think that confuses two things - and I certainly remember doing 100 in Mk1s! One is the engineering constraint, which definitely did distinguish between bogie types. The other, which @5944 highlights, is a regulatory requirement which long postdates that, and explicitly limits the speed of Mk1s used behind steam.

Like him, I simply don't get why the permitted speed of a vehicle should vary based on what is hauling it.

 

I remember coming back from Euston to Manchester once in 1983 in a Mark 1 SK, at 100mph behind an 86. Happy days!

 

Don't steam engines ride very differently to diesels? Would this have an effect on the train, at least the first couple of carriages or even the first bogie?

 

Possibly - which is why I'm curious for someone with knowledge to explain.

 

Possibly, but both the 100mph run and the Ebor Flyer ran with 60163's support coach behind the tender, and the latter has Mk1 catering vehicles in the formation. It does seem like an arbitrary restriction.

 

Sorry I'm a bit late to this discussion but why would the ORR even consider the possibility of not permitting Mk1s or any other coaching stock to run above 75MPH behind a steam loco, given that steam locos are not permitted to run above that speed anyway. Surely the maximum speed of any train is governed the slowest vehicle in the consist which in this instance is likely to be the steam loco hauling it. Any other ruling is quite unnecessary as far as I can see.

Peter

 

That's the question. The rules appear to specifically restrict MK1s (and only Mk1s) to 75mph behind steam, irrespective of the vehicle's plated speed, and irrespective of the locomotive's permitted speed. No one's disputing that the slowest vehicle will set the maximum speed; what's odd is that the rules appear to double down on that.