That was too obvious. Then again, this has dragged out for so damn long I'm just going to give it to you.
It's the camshaft box for the older stainless steel surburban electric cars. Their motors had a combination of field and rotor windings, which could be varied to give different torques(is that even a word?) depending on which were wired.
There were 4 notches on the driver's master power controller; the driver would cycle through these as they picked up speed. Each one would be a different combination of motor windings and resistor grids, and each would produce a different torque output best suited to different conditions.
The easiest way to implement this was with a camshaft box- hence these cars were known as 'camshaft cars' in contrast to the 'chopper cars', which used a thyristor-based system to 'chop' up current (PWM, basically) instead. The pilot motor would rotate the contacts (which were triggered by the individual cams on the camshaft), which in turn switched the motor windings and resistor grids. Consequently there was considerable 'lag' while cycling through notches on the master power control, as the camshaft would have to complete a full cycle before returning to the selected position.
One of the most notable effects of this was jerking as the driver cycled through these notches; they were best felt on a stretch of flat rail when there was little to no slack between the cars. The chopper cars eliminated this jerking, however, they would 'sing' whenever the thyristors were engaged.
Here's a short recording of said 'singing' (turn your volume up, it's quiet)
If it had two rows of pins, i may say printer cartridges chip resetter, but with only one row of pins ..... no ideas, if is not a charger of some type .....