No matter what I seem to do on the train loco the overlay may show Train Brake settling to 0% in lowest setting on lever but the F5 display shows always (all trains tried so far) at 17% with the term Hold Lapped next to it. I read some trains may exhibit this as an advanced feature but not sure about that. I've also re calibrated Raildriver several times with no change.
Those locos usually use a variation of the old setup, which roughly goes like this, literally a range of movement of the brake handle: 0-5: Release (actively spend air/steam to accelerate air flushing out of the pipes) 5-15: Running release (partially open pipes to let random air out, low end fully open, high end barely, helps tiny releases) 15-30: Hold = Lapped (pipes closed) 30+ = Apply (the higher, the more open, hence faster application, with 100% being the fastest) You're supposed to run in Running (doh) but you can also choose to Hold (difference is, air can build up slowly in real life). Sometimes numbers are a bit different but this is roughly how 17% makes sense. It simply means for the script that there is no air movement. Usually what scripts do is they flip-flop between Apply-Hold and Release-Hold depending on difficulty. Core TSC doesn't care too much about physics so air pressure change is usually a fixed rate, and very rapid at that. When you have a long train, it takes a little longer for changes to happen. I doubt it's as extreme as some settings do, but in our territory cargo trains usually scream a bit when starting, suggesting the brakes are still on a little bit, despite released. (US trains with the triple valve apply and release quick and release fully, ours have partial release iirc.)
On some steam locos, like the excellent VW K1, the lap position is described as “Running” and goes up to something like 43% before Apply. Part of the problem is the hangover from MSTS of using % based movement for brake application when the lever should move straight from one position to another rather than sliding through the range. Even more apparent on modern trains such as Sprinters with stepped braking, e.g. 1, 2, 3 and emergency where you still seem to slide through percentage rather than straight to the notch.
TSC offers all needed settings. You can define a lever as notched, if it should "snap" to notches or not, if it has irregular notch steps where you can define what's happening at each percentage, and give individual notch names instead of percentage.
Alot of good information thanks. The outstanding question for me is still when Brake Lever is at the bottom of it's travel and my F4 gauge shows zero but my F5 overlay shows 17%. Which is the real number? These Locomotives that exhibit these characteristics are diesel.
0% is often Quick Release on M8 brake valves. 17% makes perfectly sense for running position. F5 should show 0 psi on the brake cylinders. See the running position on the correctly modelled AP Class 37 for example. It is mapped to 20% of the handle range here. Service range is from 40% to 68%. On older unscripted locos, the handle position is often mapped directly to the brake force or the Simulation.bin's defined InitialReduction psi value. The game has multiple core brake positions to define for your loco (Release, Hold, HoldLapped, GraduatedSelfLap, GraduatedSelfLapLimited... etc..). Most modern DLC override this with scripts to have more realistic behaviour. For more in-depth information, see the dev docs. These are the brake positions the core is offering: Old Kuju steam locos were using simplified brakes, in reality there's no Lapping position on these, you'd control and hold the pressure using the ejectors.
Both You see the brake handle on the F3/F4 HUD. This is yours. You see the internal brake handle on the F5 HUD. This is managed by the script. Might be a design bug of sorts, but I suppose most people use F3 to drive and F5 for debugging so it is helpful like this. Listing all stuff on F5 could be too much. On some locos the external and internal handles are either the same, or mapped directly, so they show the same. Many other they don't. For example, on most modern stock you have a combined handle. Some trains (like the 166) apply power above the line and air brakes below. There is no additional handle. Other trains (like the SD70) apply power above the line and dynamic brakes below. There are separate train and loco brake handles. Sort of a combination, most continental electric trains these days have one power handle and one brake handle, the latter managing both air and electric brakes, based on speed and sometimes other settings. (In fact, on automatic trains like with Lzb these handles are strictly fly-by-wire.) MUs, trams often just have a single lever with a power and brake range, combining all the above: power, e-brake and air brakes.
