Change wagons capacity according train max speed?

[MagicBuzz]

Hello,

I'm still working on my French trainset and now I'm focusing on the wagons.

I see capacity of French wagons is different according to the speed of the train:
By example, a covered "Etat 1" wagons can load:
Petite Vitesse (low speed < 80 km/h) = 20 t
Grande Vitesse (high speed = 80 km/h) = 10 t

Is there something I can use to determine the max speed of the entire train to set a different capacity?

Or should I create two different wagons, one limited to 50 km/h and the other one at 80 km/h ?

[michael blunck]

Cargo capacity can be modified by using a callback (property). But generally a better solution would be to use different wagons.

regards
Michael

[Transportman]

In NML, you can change most properties in the graphics block to point to a switch that depends on cargo_subtype (in case you treat them as liveries) or other variables of either the wagon itself or the front engine to get the behaviour you describe (by having switches for cargo_capacity and speed), but as Michael indicates having separate vehicles is usually the better option for users. If you combine them in one vehicle, you somehow need to convey that information to players, requiring them to read text somewhere (either in some separate readme or in the purchase menu) and make a mess of purchase menu sorting, so keep it simple and use separate vehicles for vehicles with different properties.