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Professional driving policies

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ComUtoR

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It goes without saying that this type of driving is only really viable in tunnels where adhesion isn't an issue!

A previous PDP forced us to use step 2 first because of adhesion. The intent was to force the WSP into action. Engineering was not happy with that policy. It was also in place because not all units apply sand in all brake steps. By using step 2 at all times it meant that sand would be applied in any unit you were driving. I don't like auto-sanders and prefer manual sand (which I use quite liberally) but it does highlight why bespoke policy is needed.

Then of course, we were discouraged from using sand on accelleration and also discouraged from using it too much, in case the next Driver needed it. PDPs really are a blessing and a curse.
 
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43066

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It's interesting how the latter is so true. On ours the power/brake controller is stepless and has an optical device inside which judges what position the driver has selected. I *presume* most stepless ones on modern trains work on the same basis, with certain positions (e.g. emergency) hardwired? I've always assumed that accounts for at least some variability.

Quite possibly on the era of stock I’m thinking of (early 2000s). Presumably on the very modern examples - class 700 etc,) the brake lever just feeds directly into the control computer and is no different to clicking a mouse?

Does that apply on a train with dynamic brakes? We have the situation that going from full service to emergency will inhibit any rheo/regen braking and switch to full EP braking, which can result in a notable lag when the train doesn't seem to slow down at all. Likewise it always feels like the friction brakes then take time to take hold (especially if the train has been being driven gently up to that moment).

We had a period on ours when the rheo braking was completely isolated for testing purposes, which was shall we say interesting! Apart from regular instances of burning smells or in some cases reports of smoke spewing out from under the trains or even inside, braking performance became *extremely* variable.

That’s a good question. Certainly the stock with dynamic brakes that I’ve driven switches the system off if emergency is engaged so then you are using *just* the three step friction brakes.

The dynamic braking must also be calibrated to the brake force as determined by weight to ensure consistency.
 

bramling

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Quite possibly on the era of stock I’m thinking of (early 2000s). Presumably on the very modern examples - class 700 etc,) the brake lever just feeds directly into the control computer and is no different to clicking a mouse?

There must be some way of converting from a mechanical device to a software system, though no doubt the method on the newest trains will probably be less clunky than on 1990s stuff!


That’s a good question. Certainly the stock with dynamic brakes that I’ve driven switches the system off if emergency is engaged so then you are using *just* the three step friction brakes.
The dynamic braking must also be calibrated to the brake force as determined by weight to ensure consistency.

I suppose there must be a difference between older pure-EP stocks designed and maintained for all braking to be done using friction, and those stocks where there's the expectation most braking is done by rheo/regen. On the latter it's certainly the case that watching the brake cylinder gauges there will be a spike of friction braking before the rheo takes over and the gauge returns to zero, then in virtually all cases no friction braking until around 10 mph. Shows how much of a saving in brake wear there must be, as well as dust created!
 

driver9000

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A quirk of the three step brake I was taught was that, if the train is heavily loaded, emergency wont’t necessarily give you any more brake force than step 3. The air suspension varies the brake force in each step according to weight so that braking performance remains consistent. Once you’re packed to the gunnels, and max pressure is being delivered in step 3, that’s your lot!

Having worked with both, I must say I much prefer using a continuously variable brake, which allows a lot more control and finesse, than just having the three steps.

The point of Emergency on EP 3 step brakes was to kill the electrical feed to the brake units in the train to ensure all vehicles gave maximum braking effort. Modern units will give an enhanced Emergency brake pressure but as you're aware this wasn't the case on 3 step EP units which gave 3-3.5 bar(ish) in Full service or Emergency. I much prefer the stepless brake I have now.
 

bramling

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The point of Emergency on EP 3 step brakes was to kill the electrical feed to the brake units in the train to ensure all vehicles gave maximum braking effort. Modern units will give an enhanced Emergency brake pressure but as you're aware this wasn't the case on 3 step EP units which gave 3-3.5 bar(ish) in Full service or Emergency. I much prefer the stepless brake I have now.

I thought everything that was designed in that way had been modified so that the emergency position *always* (theoretically!) gave an enhanced rate of brake force, following various incidents over the years? Or are there still fleets not modified in that way?
 

tiptoptaff

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I thought everything that was designed in that way had been modified so that the emergency position *always* (theoretically!) gave an enhanced rate of brake force, following various incidents over the years? Or are there still fleets not modified in that way?
Some of our units don't have additional brake pressure in emergency. Emergency is the max pressure available in step 3, with automatic sand and the electrical signal to all three train wires cut. Nothing extra unless you're lightly loaded.
 

bramling

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hexagon789

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Or are there still fleets not modified in that way?

I remember reading that some fleets couldn't be upgraded because 12%g deceleration required the bogie frame to be strengthened or something and that couldn't be universally applied. Not sure if that's entirely correct
 

driver9000

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I thought everything that was designed in that way had been modified so that the emergency position *always* (theoretically!) gave an enhanced rate of brake force, following various incidents over the years? Or are there still fleets not modified in that way?

Nothing I signed with 3 step brakes gave enhanced brake pressure in Emergency. All Emergency did was ensure the full brake pressure was applied through the whole train.
 

43066

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I thought everything that was designed in that way had been modified so that the emergency position *always* (theoretically!) gave an enhanced rate of brake force, following various incidents over the years? Or are there still fleets not modified in that way?

Networkers and 319s are two such examples. 319s don’t have rheostatic braking either.

I suppose the point is that there’s always going to be a maximum brake force any system can produce and step 3 pressure will only ever = emergency when the train is crush loaded (as I understood it). Ensuring consistent braking performance in each step at all weights is more important than leaving something “in reserve” for the sake of it.

As others have said, the more important point is that emergency breaks the continuity wire and *always* ensures max brake force will be applied. That’s why it’s vital to not hesitate to use it when necessary!

I’ve “dropped the lot” three times in the last year: twice for signals going back, once for a trespasser.
 

bramling

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Networkers and 319s are two such examples. 319s don’t have rheostatic braking either.

I suppose the point is that there’s always going to be a maximum brake force any system can produce and step 3 pressure will only ever = emergency when the train is crush loaded (as I understood it). Ensuring consistent braking performance in each step at all weights is more important than leaving something “in reserve” for the sake of it.

As others have said, the more important point is that emergency breaks the continuity wire and *always* ensures max brake force will be applied. That’s why it’s vital to not hesitate to use it when necessary!

I’ve “dropped the lot” three times in the last year: twice for signals going back, once for a trespasser.

I think I'm right in saying rheo couldn't viably be provided on classes 317-321 due to the single motor car not being sufficient to make it work properly, which is presumably the same on stuff like 455 & 456.

Are there any post 1990s fleets lacking enhanced emergency braking?
 

philthetube

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Does that apply on a train with dynamic brakes? We have the situation that going from full service to emergency will inhibit any rheo/regen braking and switch to full EP braking, which can result in a notable lag when the train doesn't seem to slow down at all. Likewise it always feels like the friction brakes then take time to take hold (especially if the train has been being driven gently up to that moment).

We had a period on ours when the rheo braking was completely isolated for testing purposes, which was shall we say interesting! Apart from regular instances of burning smells or in some cases reports of smoke spewing out from under the trains or even inside, braking performance became *extremely* variable.
With S stock, LUL, it feels as if at 60mph a full service brake is better than emergency and the point at which emergency is better is around 40 as rheo becomes less efficient at lower speeds and friction improves.
 

37057

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There must be some way of converting from a mechanical device to a software system, though no doubt the method on the newest trains will probably be less clunky than on 1990s stuff!




I suppose there must be a difference between older pure-EP stocks designed and maintained for all braking to be done using friction, and those stocks where there's the expectation most braking is done by rheo/regen. On the latter it's certainly the case that watching the brake cylinder gauges there will be a spike of friction braking before the rheo takes over and the gauge returns to zero, then in virtually all cases no friction braking until around 10 mph. Shows how much of a saving in brake wear there must be, as well as dust created!

In terms of the Desiro Classic era theres an encoder on the PBC that transmits signals to the brake control units via the central control unit / MVB. The PBC also has discrete three step brake positions and signals hard-wired inputs to the brake control unit directly.

Desiro City era trains have no hard-wiring from the PBC - it's all done using ethernet (except emergency). There are two encoders for contingency from what I can tell.

The brake control units apply a small amount of brake pressure just to take the slack out of the calipers when using rheo/regen, ready if the latter drops out.
 
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The Rulebook is the Network Rail standard. Every TOC adheres to this. Its their track, follow their rules.

Bespoke rules and policies are needed because of the insane number of variables across the entire network. There are huge disparities with Traction and how each performs so you would numerous sub rules and policies each time.

20@200m from the Red is far better than 20 at the magnet. There are many magnets where if you hit it at 20, you wouldn't be able to stop for the Red.

There is also another problem of... I don't work for Network Rail. My TOC takes full responsibility for my actions. Therefore I drive to their additional set of rules and policies. If Network Rail were to implement local policy then they would have to take full responsibility for those whose polices they are setting. I'm not sure but I don't think Network Rail want to set every single policy for each TOC
Fair comment, mate. Thanks for that repy
 
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