Help with loco sound please

Bill69

New member
Can anyone tell me how to control the chuff volume in a steam loco? I have two different locos on the same route with the same engine sound.
One loco has chuff sound that is just as I like it, clearly audible, the other loco's chuff sound is very quiet, I can hardly hear it even when it is pulling a load. As I said above they both have the same engine sound, just doesn't make sense to me.
 
Last edited:
Hi Bill69
The volume of the sound is in part controlled by the enginespec; as well as the enginesound.

If you use the same enginesound on two different locos, the volume will be different due to the enginespec.

Unfortunately I cannot specifically remember which values may affect this. I think from memory it's related to the cylinder values, boiler pressure (as that controls steam chest pressure to a degree), and the 'test' values (cut-off/speed/etc).

Regards
 
Zec, if it's based in part on steam chest pressure then the steam-chest-max-flow tag will have probably have a big effect. Under normal conditions this limits the maximum steam flow from the boiler. If set too low the steam chest pressure drops too fast with speed. I would think it should be determined by the max evaporation rate of the boiler since in Trainz under normal conditions all steam from the boiler exits thru the cylinders. For a valid "test value" you mention it should match steam "consumed" by cylinders. By normal I mean steam blower off and safety valves closed. For real locos there are other routes for the steam to exit but if you're doing mass balance for steam boilers in Trainz that's it.

However the testing I've done in game doesn't show the same relationship between the max steam flow rate and the steam consumed in the cylinders that I'd expect to see in real locos. For a given test point I see less steam consumed by the cylinders in Trainz. I also find the mean effective steam pressure in the cylinders in Trainz is higher than in real locos. There's a disconnect with real world physics there somewhere.

I'll note that the TrainzWiki documentation is not correct for the steam-chest-max-flow tag. Units are in moles per sec not kg per sec as stated. IIRC blower-max-flow is also wrong. Units should also be moles per sec not kg per sec. The flow rate units for the other 2 routes for steam to exit the boiler: high and low safety valves are correct - kg per sec. If N3V can find a way to confuse users it would appear they don't hesitate to it.

Bob Pearson
 
Last edited:
Thanks for the replies Zec and Bob,

I'm afraid Zec's reply does not compute. The boiler pressures are much the same, good sound = BP 225psi quiet one = 245psi. Good sound 185 steam chest max flow, quiet one 195 steam chest max flow. Cylinder volumes, Good one 0.13344 m^2 Quiet one 0.15468 m^2 both 2 cylinder locos.
This shows the quiet loco has a slightly higher BP and larger cylinders requiring a larger steam chest flow, so it is generating and using more steam therefore should have a louder exhaust.

Actually in a real steam loco the blast pipe size makes a big difference to the sound and how well the boiler steams.

Cheers,
Bill69
 
Last edited:
Bill, are the 2 especs and sound assets available anywhere like on DLS?

Bob Pearson


Hi Bob,
Only one of the e-specs is available on the DLS, kuid2:243294:1005:2 for the BR 4MT 2-6-4T The engine sound I am using is kuid:123250:100141.

The e-spec for the other is not available as it is a WIP

Cheers,
Bill
 
Thanks for the info Bill. I can't get kuid2:243294:1005:2. It comes up as unknown asset - maybe kidnapped as payware or something. kuid2:243294:1005:1 is there but doesn't match values you posted above. The sound asset, kuid:123250:100141, seems to work fine though with BR 4MT 2-6-4T and kuid2:243294:1005:1. But that doesn't really say anything about the problem you presented other than the sound asset, that I've also used before, seems to work as it should.

Bob Pearson
 
Hi Bob,
the e-spec kuid2>243294:1005:2 is an update maybe I haven't uploaded it. 1005:1 should be much the same except for an increase in BP and minor de-tuning to stop the safeties from blowing too often. I am still baffled as to why kuid:123250:100141 is so quiet in another loco. I have increased the steam-chest-max-flow to such an extent that is is very difficult to get it to start off in cab mode. I now really have too much steam-chest-max-flow and it is still very quiet.
I have gone to the extent of reducing the decibels for the track sound and can't hear the loco at anything over 40mph.

Cheers,
Bill
 
Back
Top