Demise of the AWS Bell & Horn

[O L Leigh]

A though occurred to me the other day that we are probably about to lose the AWS Bell and Horn from our mainline fleets.

As far as I am aware, the various PEP classes (Cl313-5, Cl507-8) have them along with the LMR Cl317/1s, but all of these units are now facing large scale withdrawal and replacement. I can't think of many other major fleets* that still have a genuine bell and horn instead of the more modern electronic AWS chime. The only other candidates are HSTs (although I'm unsure if these were retained when refurbed) and at least come Cl455s.

* I'm using this term to differentiate them from what I refer to as heritage mainline traction, such as Cl37s.

 

[hexagon789]

A though occurred to me the other day that we are probably about to lose the AWS Bell and Horn from our mainline fleets.

As far as I am aware, the various PEP classes (Cl313-5, Cl507-8) have them along with the LMR Cl317/1s, but all of these units are now facing large scale withdrawal and replacement. I can't think of many other major fleets* that still have a genuine bell and horn instead of the more modern electronic AWS chime. The only other candidates are HSTs (although I'm unsure if these were retained when refurbed) and at least come Cl455s.

* I'm using this term to differentiate them from what I refer to as heritage mainline traction, such as Cl37s.

I can't remember if 318s have them as the 314s did or if they lost them when they were refurbished with the cab gangways removed and so on. You could hear the bell quite clearly when sat behind the cab, especially so with the 314s I found but it's been quite a while since I've been on a 318 AND consciously thought about it!

 

[O L Leigh]

I would have guessed that, as the Cl318s are similar to the ER Cl317/2s, they would also have had an AWS chime from new. But then I've never been on one, so I can't say for certain.

 

[Taunton]

Has to be one of the last concepts of Churchward to survive, from GWR ATC. The bell was rung directly from the current (about 15v) in the ramp. The horn (called siren by GWR) was sounded by the dead ramp causing a vacuum brake valve to open, the sound was made by the actual air inrush.

BR always tried to distance 1950s AWS from 1900s GWR ATC, but the operating signals in the cab were the same.

GWR ATC could also give an intermittent hoot at a double yellow, to distinguish it from a single yellow, this was done by feeding the ramp with negative current instead of positive, thus the ramp could give three indications (negative/positive/dead), whereas AWS by its design could only give two.

 

[4F89]

Class 86's are "classic" in this way

 

[ainsworth74]

The horn (called siren by GWR) was sounded by the dead ramp causing a vacuum brake valve to open, the sound was made by the actual air inrush.

Oh that's interesting! I'd always assumed that it worked in what you might consider a "conventional" fashion rather than by drawing air into the horn!