Hi! I’m new to Unreal and I have been trying to make it so that when a character in third person approaches a rail cart object, with a press of a button he can push/pull the cart along the track. How complex is this? I can’t find any example online of the spline movement being triggered when a character pushes/pulls. I really appreciate any help, and the more in-depth and beginner friendly, the better 
Hey @thomasbrett1995 how are you??
Welcome to the forums and to Unreal Engine! Hope you are having a good time!
Regarding your question, I highly recommend you to watch this video for the “push the object” part of the feature:
And then watch this other video to make the object follow a spline:
You will need to combine those two feature to make what you want, but I think it will be useful for you!
Of course, you have to use the force applied by the player on the object for movement instead of the movement of the object itself (as you can see in the second video) but it should be easy to replace.
Let me know if you need more help!