Capsule Physics issues

Hi, I made a project from scratch to learn to use ue4. And even more, I have used a basic pawn.

All good, until I wanted to implement gravity.
I have made my capsule

    RootComponent = CapsuleCol
    CapsuleCol->InitCapsuleSize(50.f, 100.f);
    CapsuleCol->bHiddenInGame = false;

Ok, everything works just fine, but when I get on an inclinated plan, I just rolling around…
How I can make physics work only with z axis?