There is a reference by an ex-HBS employee to electric trucks being distributed in the morning and retrieved at night from the dock areas. At first I assumed these were road trucks, but I have come to realize they were actually much smaller devices for moving around pallets, boxes and loose materials. How long these were in service, I don't know, but given the age of the employee, there is a good chance that they were in service still in the 50s.
This will make a nice operation event as well as another 3d modeling project.