Our Appendix to the Rulebook instructions are that they’re only required during snowfall or if train passage is disturbing snow. I’d say it depends how heavy the falling snow is as to whether this is necessary.If it’s just a light flurry with hardly anything on the track, are you going to do what your instructions are regarding RBTs and speeds?
For non- traincrew, could you please translate?RBTs
RBT - running brake test. Additional ones are carried out during snowfall or snow being disturbed by the passage of trains. Or also during extreme cold weather after 66734 derailed due to the brake rigging freezing. These are carried out every 3 to 5 minutes and are a full service brake application with a speed reduction of at least 10mph for all brake types. Disc brakes trains also have to run 10mph below line speed down to a minimum of 50mph.For non- traincrew, could you please translate?
Running Brake Test.For non- traincrew, could you please translate?
I was about to say the same but now I think it's something like a rolling brake test to make sure the snow isn't building up on the brakes.For non- traincrew, could you please translate?
Thanks all.I was about to say the same but now I think it's something like a rolling brake test to make sure the snow isn't building up on the brakes.
We have it on the 195’s and 331’s. Only used it once on the 195 - it’s like driving with a dragging brake!Some more recent traction units have a snow brake which does away with the need for additional running brake tests during snow conditions. The driver just has to go to the relevant screen on the train management system and press a button to engage it. Once engaged there is no requirement to carry out any additional running brake tests or reduce speed with disc braked trains. If for some reason the snow brake is not working the normal instructions for snow conditions apply. The snow brake works by gently rubbing the brakes on each vehicle in turn. The effect on the train's performance is barely noticeable except perhaps when accelerating.
Once engaged there is no requirement to carry out any additional running brake tests or reduce speed with disc braked trains.
It must be TOC (or traction) specific as I can think of traction that have a snow brake but still require a running brake test to be done regularly.Source ? Is this TOC specific ?
Cheers in advance.
The whole point of the snow brake is that it is constantly moving the linkages to prevent freezing. If you still do RBTs whilst using the snow brake function then you may as well not bother with the snow brake.Source ? Is this TOC specific ?
Cheers in advance.
The secondary reason for doing regular brake tests is so the driver can ensure the brakes are working correctly and get an idea for how much braking performance is affected. The snow brake doesn’t necessarily prove that the brakes are functioning correctly. You don’t want it to be that the only time you’re testing your brakes or getting a feel for them is when you are braking for cautionary signals, station stops or speed restrictions. But as you say, it would be dependant on company and traction.The whole point of the snow brake is that it is constantly moving the linkages to prevent freezing. If you still do RBTs whilst using the snow brake function then you may as well not bother with the snow brake.
This isn't a rulebook issue, it's TOC/traction policy. But still - why bother if you're going to do the RBTs anyway?
Or am I misunderstanding the snow brake?
It must be TOC (or traction) specific as I can th ink of traction that have a snow brake but still require a running brake test to be done regularly.
The whole point of the snow brake is that it is constantly moving the linkages to prevent freezing.
If you still do RBTs whilst using the snow brake function then you may as well not bother with the snow brake.
This isn't a rulebook issue, it's TOC/traction policy. But still - why bother if you're going to do the RBTs anyway?
Or am I misunderstanding the snow brake?
The secondary reason for doing regular brake tests is so the driver can ensure the brakes are working correctly and get an idea for how much braking performance is affected. The snow brake doesn’t necessarily prove that the brakes are functioning correctly. You don’t want it to be that the only time you’re testing your brakes or getting a feel for them is when you are braking for cautionary signals, station stops or speed restrictions. But as you say, it would be dependant on company and traction.
You do seem to not be aware of the more recent innovations of snow brake mode particularly on the CAF civity fleet. It cycles the friction brake on each axle individually periodically which solves the problems you mention. It does this even when acceleratingSame here.
This isn't my understanding of snow brake mode on the units I drive.
Not sure where you are coming from here.
Hmmmmm. RBTs go back many many years and they are/were based on the traction of the time and because ice would form within the pipes and you would need to blow out the air to keep the pipes free of ice buildup. I would say that the RBTs in the rule book mostly exist purely from a historical perspective. When I first started the requirements for RTBs were pretty extensive (Does ABBBA ring a bell ?) Now my only RBTs are after leaving, but before my first stop and during snowfall. The new style rulebook allows TOCs a greater amount of flexibility and to allow for local stock requirements.
Maybe, what is your understanding ?
Mine is that the 'snow brake mode' puts the discs and/or treads in continuous contact so that they warm up and prevent/reduce the build up of ice. This wouldn't prevent ice build up in the pipe or brake cylinders. (which was what the snow RBT was all about)
The last unit I drove with 'Full Service' was a 319 and was still based on the driving principles of 'amps and air' Modern units are very different and I can understand the reduction of the need for RBTs. With the units I drive now I don't need to do a personal brake test (because of a recent mod) and a couple have an 'automatic brake test' and will even self test the DSD.
You do seem to not be aware of the more recent innovations of snow brake mode particularly on the CAF civity fleet. It cycles the friction brake on each axle individually periodically which solves the problems you mention. It does this even when accelerating
I'm talking here specifically about additional RBTs during snow. I understood these were not to determine the braking performance of the train but rather to prevent the freezing of mechanical components in the brakes. If you remove the risk of the freezing via a snow brake function then there should be no reason to do more RBTs than normal just because it is cold (assuming the snow brake does in fact prevent freezing).The secondary reason for doing regular brake tests is so the driver can ensure the brakes are working correctly and get an idea for how much braking performance is affected. The snow brake doesn’t necessarily prove that the brakes are functioning correctly. You don’t want it to be that the only time you’re testing your brakes or getting a feel for them is when you are braking for cautionary signals, station stops or speed restrictions. But as you say, it would be dependant on company and traction.
My understanding was as bengley posted above - that it cycles the brakes on the train, activating each brake cylinder one by one in a continuous 'cycle' throughout the train. I wasn't aware that older traction does not operate in this way and if older traction does simply keep a bit of friction on the braking surfaces then I can of course see that RBTs would be useful to prevent cylinders/air pipes freezing.Maybe, what is your understanding ?
Mine is that the 'snow brake mode' puts the discs and/or treads in continuous contact so that they warm up and prevent/reduce the build up of ice. This wouldn't prevent ice build up in the pipe or brake cylinders. (which was what the snow RBT was all about)
What units do you drive with a snow brake out of interest?This isn't my understanding of snow brake mode on the units I drive.
Yes, TOC / traction specific. On class 195 / 331 the snow brake continuously cycles the brakes throughout the train as mentioned above. I wasn't aware that some units apparently have a "snow brake" that functions differently.Source ? Is this TOC specific ?
Cheers in advance.