Iowa Traction Dynamometer

The development of Agricultural Engineering as a distinct brand of technical education created a need for special laboratory apparatus and equipment.

Jay Bownlee Davidson B.S., M. E., University of Nebraska 1904, designed the Iowa Traction Dynamometer in order to make a successful study of the draft of field implements. The apparatus design was presented to the Department of Agricultural Engineering, College of Engineering University of Nebraska for his Professional Degree of Agricultural Engineer in 1914. This was the first such degree ever awarded. When designed, Davidson was then already Head of the Department of Agricultural Engineering at Iowa State University.

This apparatus was designed to be most useful and satisfactory in connection with the testing and study of farm machinery and farm motors. This traction dynamometer was very ingenious in that it not only recorded the pull on a strip chart but also calculates the average pull over a given track length.

As you can see from the picture below, this dynamometer could be used to measure the horsepower that could be could be developed by a horse.

The dynamometer was mounted between a single tree and a load unit that was a weighted sled. The pounds of pull was recorded on a strip chart and a very clever mechanical integrator multiplied the load times the distance traveled, and, using a stop watch, horsepower could be easily calculated.

Tractors were just being introduced and farmers desired to know how the load they pulled compared with that of horses, that were the dominant source of power for farming.

The system wasn’t used much because of its complexity and instability on the field, although it was actually manufactured at the time by Central Scientific Co. of Chicago. Date/Range:1912-1914

One of these commercial models, pictured above, is a part of the dynamometer collection at the Larsen Museum. (Inventory No: 669 DT)