110HP Case Steam Tractor Pull Pinckneyville Illinois August 15 2014

For those interested in knowing a little more about the science behind this, I’ll explain a bit about the torque of a steam engine. Steam engines and a DC electric motor are the only two power sources that have 100% torque output at 0 RPM. For a steam engine, this is because the piston is pushed by steam, which is an expansive power source. When the engine is idling at about 250 RPM, the governor that controls the flow of steam to the engine is not very far open, and the steam in the cylinders are not using a lot of the expansive force of steam, as it is in and out of the cylinder so fast. As a load is aplied to the engine, the RPMs will fall off slightly and the governor will open up, supplying the cylinder with more steam. Eventually, the RPMs will fall enough to a point that the governor is just wide open, allowing 100% flow to the engine. This point would be the maximum horsepower point of the engine. This engine was rated from the factory as 110 HP at around 250 RPM. At that RPM range, it can put out around 3,000 lb/ft of torque. From that point on, as the load is increased, the engine RPMs will start to drop off, using the longer time in the cylinder to get more expansive force out of the steam. This leads to the horsepower dropping off, but the torque continuing to increase. The engine will continue to make less horsepower and more torque until it gets down to 0 RPM. At that point, the steam in the cylinder is applying maximum expansive force on the face of the piston. In other words words, 100% potential torque, but no horsepower, as horsepower is dependent upon a motion variable. I hope that makes sense. I tried to keep it all as simple as I could.