Top Speeds Question

[Mr Bones]

I'm trying to find information about the top speeds of locomotives both forward and backwards. This is only ball park figures and doesn't have to be spot on. I can generally find Diesel speed info quite easily, but I'm struggling with Steam. Does anyone know a resource (web site ideally) that would list this information. It's for a variety of locos of different age & size.

[glencairn]

I stand to be corrected, but as far as I am aware no such thing on a general basis in respect of British steam engines, although one or two classes, over the years, had individual maximum speeds imposed on them.

Glencairn

[Mr Bones]

So is there no information anywhere that would state that a Class 4P LMS 4-4-0 for example could reach a speed of.....?

[Walkingthedog]

Not really sure why we would need to know.

[LC&DR]

The speed of trains is defined by the Rules and Regulations and by the practicalities of operation.

Railway Companies issued Rule Books, Working Timetables, Books of Regulations and Instructions and also paper instructions to Locomotive Depots, Signal boxes and Stations. When staff came on duty every day it was their responsibility to look at the notice board and see what was newly issued. They were allowed time at the beginning of their shift to do this. The staff who compiled the timetable needed to know the permitted speed for the route, and the vehicles which made up the train and the speed a locomotive was capable of so they could work out how long it would take to go from one station to the next.

The description 'train' also included a locomotive running by itself with no carriages or trucks. Railwaymen called this 'running light'.

Passenger trains were permitted to run faster than goods trains so locomotives intended to work one or the other were usually capable of running at the appropriate speed. An express passenger locomotive usually had larger driving wheels, but a goods engine had driving wheels of smaller diameter. This was to match the number of rotations of the wheel to the number of strokes of the piston.

The line of route also regulated how fast trains might go. Lines with extra sharp curves were more restricted so that trains did not suffer from centrifugal forces which might discomfort the passengers and crew and in extreme cases cause a derailment. Trains took quite a time to stop so the amount of distance required to do this so faster trains had to have a greater allowance so if the warning for a restrictive signal aspect was closer then train speed had to be kept low. Lines on which stations were closer together tended to be slower than those where signal boxes were far apart. The permitted speed for a route calculated by these factors was usually published in the appendix to the working timetable.

In steam days goods trains were not fitted with automatic brakes and relied only on the brakes on the locomotive and in the guard’s van and therefore took longer to stop. Goods trains therefore were restricted in speed. Certain types of wagon were restricted to lower speeds, wagons with vacuum brakes were usually permitted to run at 45mph, wagons with handbrakes only were often limited to 35mph. Heavily loaded wagons were also required to run more slowly than empty ones.

Passenger carriages were generally allowed to run at 90 mph unless a lower speed applied.

Lets us look at some specifics,

The following restrictions applied to the Eastern Section of the Southern Region in 1960.
Locomotives hauling trains may run up to the permitted maximum for the route with the following exceptions.
Class W 2-6-4T maximum permitted speed 45 mph
Class Q and Q1 0-6-0 maximum permitted speed 55 mph
Class Z 0-8-0T maximum permitted speed 20 mph.

Any steam locomotive hauling a train tender first (i.e. backwards) – 45mph
Light engines (locomotives not hauling a train)
Diesel and Electric locomotives – 65mph
Passenger and Mixed traffic tender locomotives (chimney leading) - 55 mph
Passenger and Mixed traffic tender locomotives (tender leading) -45 mph
Passenger and Mixed traffic tank locomotives - 45 mph
Freight tender locomotives - 35 mph
Freight tank locomotives -20 mph

Trains passing through crossovers from one line to another or entering or leaving sidings – 15 mph
Trains exchanging the train staff on single lines – 10 mph

On main lines, except where a lower speed is required, or on branch lines.
Passenger trains in the London area – 60 mph
Locomotive hauled passenger trains outside London area – 85 mph
Multiple Unit passenger trains outside London area - 75 mph
Freight trains – 60 mph

Where work was being carried out on or near the line a temporary speed restriction normally had to be imposed and obeyed for safety. A weekly booklet was sent to all depots and issued individually to Drivers and Guards listing the restriction, where these were and over what period of time they had been imposed. Defects to infrastructure was dealt with similarly and in emergency these were advised out by telegram.

In all cases the lowest applicable speed always had to be applied.

[Walkingthedog]

So it wasn’t in most cases the speed a particular loco could do but the speed of the train.

[LC&DR]

Something else to consider was that a drawing called a 'Diagram' was issued to motive power depots, and to train planning offices which listed on it all the parameters for the locomotive illustrated. The maximum permitted speed, minimum curve, weights on each axle, length, height and width and other basic dimensions was printed on the diagram. Some routes had to be restricted because weak bridges or narrow dimensions would not permit the passage of certain classes of locomotive. Similar diagrams were issued for carriages and wagons.

Route restriction booklets were issued stating where trains and locomotives might go and whether speed restrictions were required when passing under certain structures or over weak bridges to reduce the forces which might cause damage.

With the introduction of TOPS in the 1970s this information was programmed into the computer which printed out warnings if locomotives or wagons were put on to trains about to travel a restricted route.

[LC&DR]

WTD
Broadly speaking that was the case. Some locos like the LMS 8F were limited in speed unless the driving wheels had been carefully balanced which then allowed them to run faster. Locos with balanced wheels had a 'star' painted on the cab side under the number.

Steam traction generally was self limiting because it took a long time to get up to speed and if it was going too fast the vibration in the cab rattled the driver's false teeth! There were some nasty accident however, with trains going too fast, (Preston, Grantham, Morpeth, Salisbury etc. etc.) but it was not until diesels with their faster acceleration did the authorities get more nervous.

[Walkingthedog]

Thanks LC, I often wondered what the cab side star was for.

[bulleidboy]

I recall reading that during the last weeks of steam several Bulleid Pacifics on the London-Bournemouth-London runs were exceeding 100mph. On the right piece of track and with the loco running well I can imagine a driver opening the regulator and saying "what the hell! Lets see what she can do"!
I'm sure other regions were the same.

From Heritage Railway Magazine - "For instance on June 26 and 28, 1967 when No. 35003 Royal Mail reached 106 and 105mph respectively, Fred Burridge was only using about two thirds regulator and 20% cut off; so about 160lbs of steam. And this was on an engine in very run down condition with the motion making so much noise that it could be heard long before its arrival. Yet No. 35003 produced no less than five speeds of 100mph or more in those last few weeks of steam".

This is an interesting read - https://www.national-preservation.com/t ... el%20track.