With the increased necessity for lumber in the expansion of territories, by the explosion in population, the logging business became an industry of problems, as well as profit. Back breaking manual hauling, flumes with water, logs dragged by animals, initiated a better means for "hauling". Hence the start in the creation of the "donkey engine", which had the power to drag logs. But then, there was the problem to haul the logs to a mill. SO, this began the "cart hauling" on wooden rails, wagons pulled by oxen, horse, or mules. A solution, but the animals were not always able to climb some of the steeper inclines, and on the "down grades", the loads could catch up to the animals, and possibly kill them.
This brings us to the creation of the Shay. That was the idea of Ephraim Shay of Haring, MI. Engines were being used, but they were of a "piston" type, and at times, weighted too much for the wooden bridges, as well as poorly ballasted roadbeds. The "powerful thrusting rods" that ran from the pistons to the driving wheels, provided uneven traction, and the wheels would spin under heavy loads and grades greater than 1 percent (1 foot of rise in 100 feet of track), and the engines would loose traction altogether. To attempt to overcome the problem, some lumbermen commissioned lightweight engines with double-flanged wheels that ran on "pole roads" of wooden rails. It was of some advancement, and this experiment gave Shay a "germ" of an idea.
Althrough the 1880s, Shay had experimented with a "radical engine", that was light and did not work as the conventional "pis ton-and-rod" arrangement. And in 1880, Shay introduced a "mad inventor's nightmare". The pilot model of the loco-motive consisted of a "short railroad flatcar", with a "wooden water tank" at the one end, and a "wood bin" at the other end. There was also the "unsightly assortment of machinery" surrounding an "upright boiler" in between. It was "lopsided with the boiler on one side", and the "geared transmission machinery" on the other side.
Unsightly? Yes, but effectively incorporated Shay's central idea. Power from the lone cylinder was transmitted by gears, not rods, to the four driving wheels in each of two trucks mounted on a single chassis - 8 wheels total. The gears were the key to greater & stedier traction. A great shaft ran from the engine to each wheel, meshing with a ring of gears on the wheel. Locked in it gears, the wheel could not spin or slip. This system entitiled the Shay to traverse a 3 per cent grade, (3 foot rise in 100 ft of track") In June 1881, Shay was awaarded a patent with a
No. 242,992, and thereby started to improve his invention with more powerful versions in the 2 and 3 cylinders.
It is just a bit of history which we take for granted. For more information, there is a web site on the Shay.
