So I've been handling a 60 years old electric locomotive all week and took some photos from the inside. It's pretty cool, feels abit voctorian mad scientist about everything. The speed/power output is regulated using a mechanical tap changer on the high voltage side (16000V).
First some random shots:
Picture of the housing for the eliptical gears driving the tap changers (bottom half of the picture) top half is a indicator that shows the position of the tap connectors and in turn how much output to the motors you have (there is also a handle to manually turn the tap changer if the motor is damaged). The grating is for safety (high voltage behind it):
If you go behind the grating you see the motor turning the tap changer and alot of safety contacts ensuring that it doesn't stop in the wrong place (between two positions):
A picture of one of the air compressors for the break system: