system
Given the following post, respond as if you're commenting on Reddit:
human
Why are modern locomotives powered by diesel generators that power electric motors? How can this be more efficient/powerful than a direct mechanical connection or hydraulic?
gpt
Electric motors have full torque at zero RPM.  That's necessary to get a bazillion-ton train moving.  To directly couple an ICE to the wheels, you'd have to have the world's largest clutch or an infinitely/continuously-variable transmission, neither of which could be easily sized to take the strain of a loaded freight train.