Dual Braked Locos

It's been a legal requirement for the brake to be operative throughout a passenger train since the nineteenth century. However, the great and good Peter Olver of HMRI took a very pragmatic view on this and agreed to many a railway using locos where application of the train vacuum brake did not apply the loco brake. From a recent conversation with a HMRI Inspector, this approach, even thougfh technically illegal, will continue to be applied as long as the train brakes will satisfactorily stop a complete train plus loco in an acceptable distance.

As a slight aside, 69023 ( LNER J72) originally had a vacuum ejector but the vacuum didn't apply the loco brakes, which were steam, as there was no form of combination valve. Did this apply to any other BR locos? 69023 has now been modified to have a BR standard combination brake valve so application of the train brake will apply the loco brake.

 

S160 5197 at the churnet valley railway has the same brake systemas 6233. the engine and tender been air braked and the vacuum created by the ejector and controlled by the m8 brake valve. the DV2 valve contols the proportional drop in air and vaccum to brake the train

Regards

 

6233 and 60019 are both fully air braked, in the sense that the brakes on both engine and tender are operated and powered by air, and controlled directly by an M8 drivers brake valve. Both engines also have a slave vacuum system for operating vacuum braked stock via a proportional valve which is controlled by the reduction in air pressure in the main (air) train pipe. The driver only has access to the brakes via the M8. That is apart from the straight air brake which is engine only. Just as on a diesel or electric loco e.g. 47 or 86 etc, and by all accounts, the brakes on 6233 are just about the best there has ever been on a British steam loco. The brake systems on full air brake locos such as these are certified by interfleet rather than the VAB. My understanding is that Bittern is undergoing formal examination for the certification process this week.

Other so-called air brake locos have different systems. Clan Line has steam, vacuum and air, because the loco is steam braked, and the tender vacuum. It can operate either air of vacuum stock, but still via the M8 drivers brake valve. Most LMS engine had steam brakes on engine and tender. 45407 for example still has them fitted, but also has air and vacuum facilities for working trains, but the engine itself is NOT air braked.



Out of curosity, what stops a driver of a mainline steam locomotive which is fitted with train air braking etc, but is not fully air braked on the locomotive itself, turning his vacuum ejector off, and losing the either the proportional brake on the locomotive, or in the case of a vacuum braked tender locomotive, losing the locomotive brakes all together?

George

 

Nothing, except they would be aware of what would happen if they did. I do know if this is actually done, but the vac may not be run to save fuel and effort, and if the res is relieased the loco/tender brake would be off anyway.

 

6233 will stop on a sixpence....

Nothing stops the driver isolating the engine brake on most engines, whether it be steam or vac braked - other than common sense and traction knowledge.