Most of the Class 66 RHTT activities (scenarios or services) begin with brake timing set to PASS[enger] rather than GOODS [freight]. Since I've been considering the RHTT wagons as freight, I've been resetting the brake timing to GOODS, but I'm starting to think that I may be wrong about this, since the ups and downs of the route have been giving me fits. So, I'd like to learn from someone who knows about this which brake timing is more appropriate for these activities. Thanks . . .
PASS timing is usually for longer vehicles akin to coaches, and GOODS is for shorter ones where you've got a lot more interconnections and slower propagation of air. It also depends on how fast the brakes apply on the wagons too. Containers would be PASS timing for example and I would assume RHTT fits into this as well based on their size and weight. PCA tankers and the like, would be more like goods timing, lots of small heavy wagons. As I understand it, it's the timing that the brake pipe is dropped to apply the brakes - in PASS mode it happens quicker, but if this would mean the loco is on its intended application much before the rear is, then you're likely to start sliding with the rear wagons pushing away, in that case GOODS timing slows it all down, so that the front and rear are more aligned and the braking is evenly spread, reduces the chance of slide at the cost of slower brakes needing more planning. Something like that. Matt.
Thank you, Matt! That's just what I wanted to know -- and perhaps this knowledge will help me operate RHTT trains more efficiently.
Not quite correct but close enough Matt. Goods timing and Pass timings related to how quickly air pressure builds up or vents from the brake cylinder. The Pass times take in the region of 2-3 seconds to build up to 90% of maximum brake cylinder pressure, while goods timing takes in the region of 18 seconds to come to force. For release Pass timings take around 18s to vent, while Goods timings take between 30 and 45 seconds. The reason for this is on longer trains the brake pipe towards the rear will react slower to changes than at the head. For example a 900m long train, the rear wouldn't even start to respond for nearly 3 seconds after the front has started to change, let alone drop sufficently to bring the brakes into full force. As such were pass timings to be used, the front could be fully applied before the rear even has does anything. This brings the risk of severe run in shocks as the rear wagons violently run into the front portion. The same is true for release, the rear will take a longer period of time for the brakes to come off fully, as such the front make be off while the brakes at the rear are still hard on. Goods timing effectively slows the rate the brake cylinders apply and release at so the pipe has time to change which will in turn make the brake application and releases much more even along the train with the brake force at the front and rear being much more equal. Goods timings are only really needed on exception long and heavy trains, or if the train is loose coupled wagons as was typical in BR days where most wagons had instanter couplings. Running such trains with goods timing was typical and most wagons were just fixed in goods timing back then. With modern wagons they will typically be much more tightly coupled and generally will run with passenger timings except if it is a very long train. A general rule of thumb would be BR wagons Goods, modern wagons Pass. For the RHTT there is absolutley no reason to run on Goods timings. Another rule of thumb is if the train is allowed to go 75mph it will be passenger times, goods timings are usually max 60mph if that.
This Tech-Doc Section has a lot of information about UK Trains & Brake Systems: https://drive.google.com/drive/folders/11eUff1VYDseHAifyRlERpLimKF2xPSFy
Okay, thanks to all who responded (especially to Matt, since he is most likely aware of how DTG programmed these brake timings as well as what they mean on the basic level that addresses my ability to successfully and satisfactorily complete RHTT activities in TSW3.
You will find that Dad Rail has u-tube videos on the class 66 - he is a real life class 66 driver (and former passenger driver) and you will find that his information on those videos generally agrees with Matt above. I heartily recommend his tubes.
