The Legacy of Caterpillar D364: Powering the Great Lakes and Beyond

1951 Caterpillar D364 Diesel Electric Set

In the ‘30s, Caterpillar entered the diesel electric generator market. Cat assembled the units in house, sourcing the generator heads from outside the company. Caterpillar was one of the first prime movers of diesel power for any possible venue and diesel generators were just another step in that direction. Besides powering their lines of crawlers and construction equipment, they also sold diesel power units, marine engines and bare engines for installation into all sorts of equipment.

While Cat made marine generators with raw water cooling, this unit has a radiator. That choice by the owners proved to be a little problematic. In looking at work orders for repairs by the various Cat service organizations over the years, we saw that overheating was an issue. One repair tech cited a 127 degree ambient operating temp when the ship’s boilers were lit. Since the diesel generator was most often used while the boilers were not lit, that probably wasn’t a very common issue. The data tag shows the engine set at 203 hp at 1200, with a 150KW rating. That is 12 horsepower and 10KW off the nominal rating of similar units from the catalogs but this engine was built to a specification and wasn’t a standard issue unit. It’s interesting to note that big radiator is from Modine.

In 1935, Cat developed a big V8 diesel, the D17000. Displacing 1662 cubic engines and commonly seen rated at 200 maximum horsepower at 1000 rpm (150 continuous), it was developed with diesel switch engine locomotive work in mind. Like other Cat diesels, it also excelled in marine and stationary work, including generators. Built around a 5.75 x 8-inch bore and stroke, torque peaked at 700 rpm making 1040 lbs-fit, but the curve was virtually flat from 550 to 800 rpm. The D17000 was in production past 1955, even as a new generation of diesels rose to take it’s place.

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The New Generation of Vee

Fast forward to 1949, when Cat introduced a new line of V8 and V12 diesels. These new engines could easily be called an evolution of the D17000, sharing the same 8.75 x 8-inch bore and stroke, but they were also considerably different. The new V8s displaced 1662 cubic inches, just like the old ones, and the new V12s made 2493 cubes. They were modular, centering around that 5.75 x 8.00-inch bore and stroke. They came naturally aspirated or supercharged and Cat spun them up a bit more than the old D17000. The naturally aspirated D364 V8 made a maximum of 265 horsepower at 1200 rpm while the D375 supercharged V8 made 335. The NA D386 V12 made a max of 400 horses and the blown D397 made 500. Of course their continuous ratings were much lower, with the subject of our story today, the D364, rated at 215 horsepower at 1200 rpm. The D364 had many uses and while potentially available to power construction equipment, we did not find any such applications using these engines.

Home, Home on the Lakes

In 1952, the Great Lakes ore boat, SS Willis B. Boyer, built in 1911 and christened as SS Col. James M. Schoonmaker, was undergoing major renovations. The main thrust was the replacement of her original 2500 horsepower reciprocating steam plant with a 5000 horsepower Westinghouse steam turbine, along with new boilers. Many other systems got updated and included in that was a spanking new Caterpillar D364, 150 KW diesel generator set.

The standard gauges, oil pressure, coolant temp and fuel pressure, plus the emergency shutoff control. A mechanically drive hour meter was also on the engine. That meter is exceptionally difficult to read. It appears to show 13590 hours.

Cat used a variety of generator heads on the sets, this one being a marine rated, 450 volt, 150 KW unit from General Electric. 150 KW is the continuous rating, with up to 234 KW available for 2 hours, heat being the controlling factor. Modularity at it’s most practical!

Remember that the Boyer had steam generators to provide electrical power when underway. The new diesel genny allowed the boat to be fully powered electrically when the boilers were shut down, for long or short periods. The big Cat wasn’t the first diesel on the ship, a US Diesel DC generator was installed in 1947 to power a new electric hatch crane and with a motor generator to convert DC to AC, it was also used to power other basic electrical systems on the ship. You can read about that generator, and the Boyer/Schoonmaker at https://www.dieselworldmag.com/diesel-engines/vintage-diesels/unsung-hero/.

The supercharged D375 variant, which made roughly 100 more horsepower than the NA D364. You can see the blower sticking out from the backside of the engine. Due to the increased airflow, dual oil bath air filters are used rather than a single. This engine is set up as a power unit with what looks like a Twin-Disc gearbox.

After a long working life, Schoonmaker was laid up in 1980 and the big Cat likely ran only a few more times after that. Still dressed up in her Willis B. Boyer clothes, the boat was purchased by the City of Toledo in 1987 as a museum ship. A museum grew around her and as she was reborn back into her Schoonmaker livery, the national Museum of the Great Lakes opened and is now a world-class maritime museum you should see.