Traxx realism improvements

[stronzio]

Some things on the Traxx are quite wrong... and have been since the prologue. Some of those are a bit on the nitpicky side, if not completely useless from a gaming perspective, but here's what I gathered so far; if I'll notice other stuff, I'll write it here (but anyone else is welcome, if they want to add something!)

Note: Traxxes come in different configurations and some things on the same very machine might work differently while being used on different rail networks, so maybe a few of these observations may be wrong in this context and/or not applicable on PKP

General:

• the “red emergency mushroom” on the central part of the desk should dump all air on the main brake pipe and also lower the pantograph(s) when pressed

• The “mushroom” on the right side, on the wall, should lower the pantograph only

• The “mushroom” on the underside of the driver's desk, also on the right, only applies emergency braking

• Traction is a bit too "reactive"; official figures say that
  • 0/100% of traction should be achieved in ~8", 100/0 in 4"
  • 0/100% of EDB in 5"
    (As a little nitpick, real traxxes usually have a small delay of a couple of ms each time you give a "pulse" on the levers, which really depends on how "old" and badly mantained the locomotive is) 
     
• Direction selector light should turn off @about 10 km/h. As a fun fact, it should be possible to press "N" or the opposite direction buttons at speeds > 3 km/h and make the loco go nuts (traction block reset-able only after stopping again)
• Battery OFF doesn't seem to work (did it in the prologue though? Can't remember). On a side note, IRL it's ALWAYS functional, even if you're cruising around at 120 km/h, which has been a source of interesting shenanigans in a few occasions
• The speedometer should have "sticky" 1 km/h increments (like the hasler, but more precise)
• Levers should be a bit less "sticky" instead, it's a bit complicated to switch positions (En76 does it a bit better?)

Brakes:

Brakes definitely need work. The whole system seems modelled on a purely pneumatic, oerlikon-like style. Real locos mount a Knorr electronic control unit that governs the main pipe/brake cyls and is fully driven by electronic valves, which is very precise, reliable and only moderately influenced by train length. The driver's valve is also fully electronic... so much so that without battery power, you can't trigger an emergency application from it 🤔

• In the sim the hi-flow charge is basically not working. IRL it's very fast and would actually fully recharge the brake pipe in a few instants, provided it's hold in that position for a while, at the cost of a ludicrous amount of air drawn from the main reservoir... which may or may not be enough in certain circumstances.  It doesn't always trigger (I think there's a cut-off that depends on the upwards pressure gradient the BCU is "sensing") but will do most of the times after a moderate drop in MBP pressure.
   
• Normal release and application are also too slow when having wagons, as if influenced by the train's length in an exaggerated way; the electronic control on the real loco should "compensate" the air flow needed and give quite consistent timings only partially influenced by this factor. As a general rule, the Red needle mostly follows more or less closely the White one (that's the desired reference pressure you're actually "setting" with the driver's valve). I'd say that atm the HFC is roughly almost the real normal release.
   
• Emergency application (either with driver's valve or the red buttons), while adequate, seems also a bit slow, the loco has a set of valves with the specific function of connecting the MBP to the atmosphere in case they're triggered e.g. via the driver's brake valve
   
• The "pilot pressure" (white needle on the brake manometer) should remain mostly "set", without considerable leakages, if you play around too much with braking, e.g. go into emergency and then release/ set it to some other intermediate value while the Red needle (MBP pressure) is still going up; they'll both eventually match
   
• "Local release" using the switch on the driver's desk, should be almost instantaneous: it will directly dump all the air in the brake cylinders by using their electronic control valves as long as it is pressed. When released, the cyl will immediately be fed back air according to current train brake setting. Note that Local release won't work, or will only partially do accordingly, if direct brake is activated; direct "overrides" train brake in this case.
  It should also theoretically work when the train is running and should also even release the ed brakes if they're on. I'm not sure it'll do if SOS valves are activated (i.e. during an emergency application).
  For context, local release is mostly used when the wagons have to be uncoupled and the driver has to "compress" the buffers to facilitate unscrewing the coupler. You brake with train brake, reverse, local release, and then apply direct brake.
   
• "5,4 bar overcharge" function should raise the MBP much faster (or at least the Pilot pressure if it can't keep up). The BCU is quite competent at "remembering" the overcharge setting, so it's very hard to lock the brakes on the wagons if you brake "improperly"
   
• The manuals says a train brake release shouldn’t cause an automatic overcharge of the brake pipe, but in practice it does even though I’m not sure with which rules exactly. From experience
  • No OC whatsoever happens if the “fast release” is used with the MBP already full
  • with a normal release a smaller overcharge (~5.2 bar) should be triggered
  • a normal overcharge (5,4) should be triggered when a fast release (HFC) happens
     
• The "train brake" lever is still misaligned, the "Hi-flow charge" position is the real "running" position: at the extremes (HFC/SOS) the lever should have a travel of about 90° starting from a ~45° angle (like this:  \ | /_ ). Here's an explanatory pic, with the lever in "maintain" position

 

• Deceleration with pneumatic brakes seems just a tiny bit too much on the weak side with loco only and no wagons
   
• Wrong max brake cylinder pressure in G & P setting and with max direct brake (looks like R value is always used).
  • "G/P" should have about 3 bar max (only difference is response time)
  • "R" ~3,8/4
  • Max direct ~4,5
    (Switching from and to g/p/r with the train brake applied also immediately influences the BC pressure and the associated timings)
     
• Brake pads sounds are wrong; also, IRL the loco actually is pretty quiet and mostly whines only with strong braking (e.g. full direct brake) and at fairly low speeds. Personally, since I know it’s hard to obtain better recordings, I’d suggest to at least lower their volume a lot and trigger them with a much higher BC pressure
  Also, brake sounds are wrong too (application/bcyls etc.).
   
• Direct brake is monitored by the vehicle logic; if the loco Is moving while it’s applied,
  • an emergency application occurs after 4’’ for speeds > 60 km/h
  • a “traction block”, for speeds up to 60 km/h, after 700m
     
• Direct brake set into full (stable) position will bypass the Wheel-slide protection built into the locomotive, in case you may want to simulate this (good luck being aggressive under rain in this case 😇)
   
• It should be possible to  command traction when there is still air in the bcyl; actually, it should always be possible provided that the brake lever is at least in running pos. and there aren't other "traction blocks" active; not sure if there are specific difference when in Polish configuration, in analogy with older locos.
   
• Atm it's possible to mess with the El/pn setting in the configuration menu, though they seem to do nothing. IRL there are some side effects depending on which setting is involved

[stronzio]

Also, if any moderator or someone from the development team is reading this: I have a few recordings which I sent a few months ago to piotrek on discord, by his request, but I'm not sure they went through. Please contact me if you want me to send those again.

[stronzio]

• Commanding traction with the train brake in "const" (not sure in other positions, will have to check again) will not work, which is right, but will do immediately as soon as you put the lever back to "running", which is wrong (you'd be in a "traction block" and would have to set it back to 0 before)
• When running light or with very light loads the locomotive should self limit the tractive effort in order to maintain a max set acceleration (I think it's 1 m/s^2 maybe? I'm not sure, but it should limit itself to about 150kN or something similar), in the sim you can Ferrari your way out if you want 😁

[Królik Uszasty]

Thank you very much for information - we will use them to improve physics of TRAXX.

 

To be honest about switching off the battery, currently it is made in the same way as in most (or even every?) polish vehicles. Switching off battery means opening battery relay, so battery is separeted from low voltage circuits. However, when converters are working, low voltage line is supplied by them and lack of battery is not a problem until converters stop working (voltage drop, opening circuit breaker etc.).

[GoppelPL]

@Królik Uszasty PM me if you need to chat about Traxx in out language (I drive them IRL as well). The battery off switch is funny, because it doesn't shut down the loco immediately (as the Elf EMU does for instance, you hit the kill switch and everything goes dark), but it's like shutting down a PC - it slowly shuts down various systems and it takes a while.

Edited December 20, 2022 by GoppelPL

[Królik Uszasty]

Some of the requested changes will be in the next patch - please check next changelog 🙂