This construction looks very simple, so, I'm going to presume that it is already discovered, but just in case, this allows to give momentum to motors. Weirdly enough, if you are going to break it, your game is going to crash, after testing it again. Here is an example of such construction. (sorry for my poor english)
@BioRenegat Yep, there's a similar setup in @Khudrat 's level Wheel of Pain (though I believe this is the first time I've seen a horizontal setup). Basically the two motors cancel out each other so the metal block can rotate in either directions. This actually also happens with draggable motors, as you might have noticed that it's a bit harder to rotate them to a desired orientation and stop them exactly there (they usually have trouble stopping immediately, as there are two opposing motors).
Here is a level I made a while ago, using this technique. Pendulum by H3xon posted Mar 2, 2017 at 8:33 PM