The four cylinder Kohler light plant was built from 1926 until 1948. These light plants were self contained gasoline engine driven direct connected electric generating 115 volt, AC, 60 cycle, 1500 watts. Also 1-1/2 KW and 2 KW, 115 volts DC. These small water cooled engines had four cylinders with a two inch bore and a three inch stroke. The AC model light plants ran 1200 RPM. The 1-1/2 KW DC light plant models ran 1000 RPM and the 2 KW models ran 1400 RPM. These generators were intended for continuous use. They were made with controls for automatic starting and stopping when a load was switched on or off. The light plant I have does not have this automatic switching device. It was used on a dragline used to strip coal. It was cranked up and run all night for lighting the stripping operation. These generators weigh about 500 pounds with a heavy flywheel and the large armature making them very free from vibration.
My generator has a serial number of 12356 indicating it was made in 1926. It is a DC model. I bought it in Ames Iowa nine years ago. It had not been used for several years. A casting that screws into the timing cover was broken that I welded and made new threads with a lathe.
A coating of oil and dirt had to be cleaned off before I could start work on it. The crankcase which holds seven quarts of oil had about an inch of mud or sludge in the bottom. After cleaning everything I removed the cylinder head and ground the valves, adjusted the valve tappets, put in a new set of spark plugs and it ran fine. This engine had a fuel pump that I removed and I installed a gas tank that would feed by gravity. I found that the generator would not work and needed a complete cleaning. The brush holders were stuck and the collector rings were burnt black. Using some WD40 and sand paper I got the generator working. I installed a volt meter to indicate the output voltage. I was not sure of the color to paint it so I used a grey paint with black trim.
I have the unit mounted on a small trailer and when I show it at antique shows I have a five cent piece that I balance on the engine to demonstrate the lack of vibration. This coin will stay balanced for a long time if there is no wind. Most spectators think I have it glued on. I have a lot of fun by kicking the trailer wheel and it falls over.
These electric generating light plants are not a rare item. The U.S. Government bought several thousands of these units for use in World War 2.
The one I have was made in 1926. "It is old enough to draw Social Security."