Large industrial wire-wound power resistor (sometimes part of a load bank or rheostat system). Used to control motor speed, reduce voltage/current, act as braking resistors, dissipate excess electrical energy as heat or test generators/motors.
Each cylinder is a ceramic core wrapped with resistance wire, designed to handle very high electrical loads and heat. Most commonly found in old factories, crane or hoist control systems, elevators and machine shops.
Very typical of pre-1960 industrial motor control systems. Could easily be WWII-era or slightly earlier. 1930s-1950s..%C2%A0Used%20to...){kind=link}