Too much iron going into cargo train!

[Arceus138]

So iv'e been starting to transport iron to my main base by train because i ran out of iron ore nearby and i needed some at my base.

My problem is that on the train that i'm using to transport iron ore I also have it transporting ammo and crude oil, but there is so much iron ore that it ends up filling up the whole cargo and noting else will fit.
Id rather only have to use one cargo because having more than one slows the train down. Is there a way i can have the amount of iron going into the train be limited to a certain number/amount?

Thanks for any replies!

Image of setup: https://gyazo.com/1a0925a67bc021e34464e6e1ac23206e (I have the inserters turned off to avoid the cargo overfilling again)

[kingarthur]

the simplest way to do it is you put filter in the cargo wagon. to put a filter on a slot you just click with the middle mouse button to set the filter or if an item is already in the slot you want the middle mouse button will set the filter to that item.

filter

filters.png (1.6 MiB) Viewed 1463 times

filter will only allow the assigned item to be in that slot. all unfiltered slots will continue to work like they normally do.

filled wagon

filters2.png (1.56 MiB) Viewed 1463 times

[Arceus138]

Wow, i forgot all about the middle click thing! I always thought it only worked for my inventory. Thanks for the reply!

[kingarthur]

your welcome. fyi mmb click doesn't work on anything else. just the toolbar and cargo wagons. if you have any other questions feel free to message me anytime. id be glad to help.