Hi; I get to the ore cart full of dynomite, but cant find the lever to…

Look to your right of the cart - notice a post between the tracks>?
You can find it by putting your mouse cursor over the post till it becomes the hand - Wear the gloves - then click on that spot - You should then get a short movie of the cart rolling to the sea - after you have laid that steal plate at the end of the tracks on the dock in order to make a ramp - that you got again, in the observation room a second time after Ariane spoke to Adam. Hope this helps...

PS - If you hadn't done so already - don't forget to take that ladder - and use it down in the mines by that washing machine-looking thing - so you can cut the wire and take that roll of dynamite located in the rafters. The ladder is near the elevator door on the platform... Do this before releasing the dynamite cart... - Good Luck!