CAT IN A TANK

1942 CATERPILLAR RD-1820 RADIAL DIESEL

In today’s world, a Caterpillar diesel in a tank seems like a naturally good idea. In World War II, however, dieselpowered tanks were not common. Certainly not with American ground forces. There are many reasons why and we’ll touch on them here a little, before highlighting an engine developed to dieselize the armored forces.

GASSY GRUNTS

The primary reason so few diesel tanks were used in WWII is standardization.

The American military and it’s supply infrastructure was set up on gasoline, as was just about all motor transport in the U.S. Diesels just did not have a large foothold in U.S. transportation systems back then and diesel technology was only just evolved enough to start making a foothold. Steam still ruled ship and rail transportation and the vast majority of trucks, even the biggest ones, were still powered by gasoline.

One of the big reasons the United Stated did so well in WWII was that we became masters at logistics, standardization and asset allocation. Speaking just of tanks, it was certainly possible to push the research and develop suitable diesels for tanks.

That was done as you will read here but after some very good gasoline engines were developed, the very practical choice made to not allocate many resources to a changeover and keep the logistics running smoothly.

Some of you may be shouting, “But gasoline powered tanks can burn!” That is true, but if you look at the true causes of tanks burning after being hit, you will find it was mostly the ammunition propellant burning. Midway in the war, our tanks were equipped with wet ammo stowage

The front (facing the front of the tank) of the engine showing the transfer case and support housing that covered the clutch, flywheel and fan. The flange at the bottom is the output that was coupled to a driveshaft leading to the transmission at the front of the tank. Here you can see a single starter and several panel type oil coolers. In production, the oil coolers were a spiral type and there were two starters. The transfer case contained a set of three gears that directed the power down from the crankshaft in the center of the engine to that flange. The driveshaft ran along the floor of the tank. We don’t have the specs, but by the appearance of the gears in the manual, the output is overdriven a little. That is supported by the engine torque measured from the crankshaft being more than measured from the output flange by about 37 percent.