What is it?!?

Nearly four tons of industrial revolution magic. American made. Wisconsin made, to be more specific. Kahlenberg 336-AT is a fine example of the type of engines which propelled small to mid-size commercial vessels on the Great Lakes from the 1920’s through the 1960’s.

Why…?!?

I like well-made and well-designed mechanical things. Kahlenberg made brilliantly designed and crafted engines. These engines were the Swiss watch of boat propulsion.

I like engines. The Kahlenberg is a real engine. This one has three cylinders. 8.5″ bore and 9″ stroke. 375rpm. 54hp. And a sound that is pure music. I distinctly recall the sound of a running Kahlenberg from my youth. It even smells cool just sitting here.

I like local history. The Kahlenberg engine was central to the livelihood of many. Reading the documentation of the period is a good lesson in how people worked, engineered and manufactured 100 years ago. The engine is symbolic of the day.

My goal is to restore the engine to running order while keeping it as original as possible.  It’s an education.  It’s a challenge. I want to see it run.

Then what?!?

I don’t know.

How does it work?

The design principles are built around the needs of the men who used them, mostly fisherman, who demanded reliability, simplicity and operational efficiency. This is an internal combustion engine. It runs on diesel fuel or most any other petroleum distillate. Gasoline was relatively expensive in the day and required somewhat more complicated engine components, primary an electrical system for generating spark. But the Kahlenberg is not a true diesel as it does not use compression for ignition but rather a “hot bulb”.  Fuel is sprayed via an injector and injector pump onto a hot surface in the top of the cylinder head which then ignites the fuel. As a kid I flew control line airplanes with a Cox .049 engine. This tiny engine worked much the same way.

The Kahlenberg is a two-stroke design, meaning each cylinder fires once per crankshaft revolution. There are no valves (well, actually there is one but it’s not part of the intake/exhaust system). Each cylinder has its own crankcase. Air is drawn into the crankcase as the piston moves up. As the piston moves down the air in the crankcase is pushed into the cylinder through ports that are exposed near the bottom of the piston travel. At the same time exhaust from the prior stoke is pushed out of the cylinder through ports on the opposite side of the cylinder, all in a single action. As the piston travels back up the air is compressed. When the piston reaches the top of the cylinder, a carefully timed and measured blast of fuel from the fuel injector is shot onto the hot bulb causing combustion.

Starting the engine requires pre-heating of the hot bulb. Each cylinder head is equipped with a “torch”. The torches run on compressed air and diesel fuel. The operator must light each torch and then wait about 3-5 minutes for the firing tube to get red-hot. At this point the engine can be started and the torches extinguished as residual heat is enough to keep the engine running.

Each cylinder has its own fuel injector. Timing and RPM are individually adjusted by the operator. A governor maintains consistent RPM, which in the case of this model is rated at a maximum of  375RPM. The operator can also control the intake air baffles to improve the air/fuel mixture.

Lubrication is performed by two mechanical oilers which precisely meter oil to all the lubrication points via 20 individual copper lines. A few systems are lubricated by running within an oil bath. Also, there are two site glass oilers for specific components.

The engine is started with compressed air. An air valve and air distributor precisely time blasts of compressed air into the cylinders. The engine can run in either direction. To reverse rotation, the engine is stopped and then quickly restarted in the opposite direction. An experienced operator can reverse the engine by “bouncing” it off the last compression cycle without using compressed air. This particular engine has a reversing transmission and clutch which negates the need to reverse the engine itself during normal operation.