Trainline/Mainline vs Brake pipe/Main resorvoir

Not having been a guard or driver but having done the train equipment course (and the mysteries of the Triple Valve) in 60's I can remember main line was 85lb and was used to replenish train line at 65lb that was used for braking. On later trains the train line was replaced by an electric wire and the braking was done from the main reservoir. No idea how the trains stop now.

I believe all trains from the 73ts to the S stock still use the latter system you described, combined with rheostatic/regenerative braking.

Main reservoir pressure on the "big" railway is usually up to 120 psi/6bar. The brake pipe used to operate at 70psi but was changed in about 1977 to 72.5 psi to make BR air-braked rolling stock operate on the same brake line pressure as European railways of 4 bar.

This involved some problems during the change-over period, as a loco that could only produce 70 psi was not able to release the air brakes on a train that had previously been hauled by a modified loco! Several times my guard and station staff have had to walk down the train and pull all the brake release strings before the train could depart!

During the change-over period modified locos had a small orange sticker on the driver's desk to warn the driver the brake pressure had been modified.

Yep, you can guess the job of the secondman and fireman at each station when we were top and tailing trains between North Weald and Ongar on the EOR, GWR Hall on one end and Class 31 or 37 on the other end!

You may be thinking of the derailment at Grantham in 1906, in which the train, descite being scheduled to call, ran through the station at speed and derailed on the junction beyond (set for the Nottingham branch as "flank protection" for a train coming off the branch). There have been many theories for this, ranging from the driver being taken ill and the inexperienced fireman failing to realise where they were, or the crew fighting, but another theory, if I recall the details correctly from an article in The railway Magazine on the centenary of the accident, was that in order to speed up locomotive changes at Peterborough, the unofficial custom was to release the brakes on the train by "pulling the strings" and closing the pipe connection between the loco and the train before detaching the loco. On this occasion no-one re-opened the connection to the train's brake pipe when the new loco had been attached. The fireman on that loco was inexperienced and, having only previously worked on light engines and unfitted freights, he was not surprised by the speed at which vacuum was built up (as only the loco's own brakes were being evacuated). As the journey from Peterborough to Grantham is a simple up hill to Stoke Tunnel and down the other side, the driver discovered that the only brakes he had were those on the loco itself only when he reached his braking point on the approach to Grantham. (The small amount of leakage in the train brakes, through not being connected to the vacuum pump on the loco, would have made little difference to the outcome). Reports of the crew glimpsed apparently fighting on the footplate could in fact have been desperate attempts to get a few turns on the handbrake. No-one heard a whistle, which you would expect passing through the station whether on purpose or otherwise, again suggesting the crew were too busy.

On vacuum braked stock there is no cock to open or shut as there I on the air brake. Pipes are either connected or they're not. That is why on the back of a vac braked train the pipe is always put on the "dummy" to ensure the pipe isn't open to atmosphere.

There was an accident in about 1978 on the ECML involving a class 55 and express at Darlington which failed to slow down. This ended up on the Bishop Auckland branch, having gone through Darlington platform at speed and knocked a DMU out of the way. It turned out "something" had gone between the first and second coached and isolated the air brake, so we only had the loco and first coach providing the brake. I was the 2nd man who helped prep the loco at Kings Cross. It turned out the "something" was the traction motor cover off the loco. Luckily there were no fatalities on that occasion.