Illinois Thresher Steam Engine

The story of Thresher steam engine No. 152


| July/August 1998



Illinois engine

Winching the Illinois engine onto our lowboy, ready to go.

35545 Highway 69 North, Forest City, Iowa 50436

History of Manufacturing

William N. Rumely, founder and president of the Illinois Thresher Company, was also the Dean of Manufacturers of threshing machinery in America. He 'devoted his entire life to engineering and the construction of machinery for threshing small grain and hulling seed. He succeeded the presidency of the M. Rumely Company upon the death of his father. Later disposing of his interests in that company, he came to Sycamore and founded the Illinois Thresher Company, where he manufactured his products.

The Illinois steam traction engine was a double geared, rear mounted steam engine. Every shaft and gear had a double bearing and there was not a stub shaft or bracket on the engine. The boiler was built larger in size than was required by the accepted engineering standards at the time. All boiler steel was rated at 60,000 pounds tensile strength, it used the best quality of open hearth boiler steel and was a butt strap seam type on all 25-80 HP boilers. It was the open bottom, direct flue, locomotive type construction. Only the highest grade of steel was used for the tubes. It was built to comply in every respect with the specifications laid down by the Society of American Mechanical Engineers and with the strictest boiler laws of all states and Canada. They were surrounded by copper ferrules to insure a strong and lasting union. Seven-eighths inch stay bolts were placed every 43/8 inches and 49/16 inches from center to center in the firebox. The boiler contained 42 2 inch flues 100 inches long. All holes in the flue sheet were drilled instead of punched to insure exact hole sizes. These were provided at both ends with large beaded heads. The steam dome was very large in size, well braced with butt strap construction, and located in position to furnish a large supply of dry steam at all times. The arch type firebox was of generous size, furnishing a chamber for perfect combustion of fuel. Their boilers were tested under hydrostatic pressure of 225 pounds of cold water and working pressure at the factory was set at 150 pounds.

After the engines were mounted, they were tested again under steam pressure of both belt and traction power. The Arnold single eccentric was the reversing device used on the engine. They used the double ported valve. This valve was not commonly used by other engine builders because of its high cost. The Illinois Thresher Company made the following three steam traction engines: 20, 22, and 25 HP.

The largest of the three was the 25 HP steam traction engine, as shown in this article. The 25-80 HP engine had a 10' bore and a 12' stroke. This steam engine was a coal, wood or straw burning engine with cab and jacket. The engine frame was the self-contained Corliss type. The cylinder, steam chest, guides and pillow block were all combined into one casting of especially tough, close grained iron that was perfectly machined and made susceptible to lubrication. The boring of the cylinder and cross-head guide was done in one operation, both tools being carried by a boring bar which insured perfect alignment of all parts. The friction clutch could be engaged or disengaged at high or low speed. The draw bar was securely attached in close proximity to the huge brackets which took the forward thrust from the rear boiler mounted axle. It was built to withstand several times its normal strain. Heavy cross bars held it in place against side thrusts. Only 63 units were built, starting at 100 and going to 163. Today only six of all three sizes remain, and only two of the 25-80 HP are known to exist.

First Owners

Engine #152, a 25-80 HP, built in 1924, was purchased from a dealer in Wichita, Kansas, along with a 36' Illinois wooden separator. It was taken to a farm a short distance west of Wichita, Kansas, where it was used during the life of the big threshing era. When the era was over, the engine and the separator sat side by side on the farm. Then William F. Merhoff of Newkirk, Oklahoma, bought the engine from where it rested. The separator which sat beside it had totally rotted down. Merhoff took the engine to his place and found another 36' Illinois separator which he used at early shows in the 1950s. In July of 1960, William Merhoff put the engine up for sale.