Harnessing Power: The Ferguson 3-Point Hitch
The history of agriculture is the story of “doing it better.” Why? Simply because “doing it better” meant producing more food for less effort expended. The result: Your wife and kids were better fed, and you got an occasional moment to enjoy life without your belly grumbling.
Perhaps the most significant of these “doing it better” changes was the shift from animal power to mechanical horsepower. But from the dawn of tractor farming, methods for attaching implements to tractors cried for innovation.
Most horse-powered implements were “tag along,” simply connected to the horse and team by means of the universal horse harness (the hitch) trailing behind the team (the power source) and transmitting pull via a single pin, and if needed, steering the implement via a wooden tongue connected to the animals’ necks.
At the beginning, tractor implements were almost universally similarly connected as with horses. A single pivoting pin through a clevis made the connection, transmitted the “pull,” and allowed the power source to swing side-to-side ahead, pulling the implement to the side for steering.
But this system presented several drawbacks. The ability to travel backward was limited (it’s tough to “push a string,” right?), there was almost no ability to steer many types of implements when moving backward, and there was limited control over the position of the working implement behind the power source.
Most importantly, in such a scenario, tractors could rear up in front (particularly when pulling up hills), flip over backward, and, more often than anyone likes to recall, crush the operator. (In a case of dark humor, the popular Fordson tractor of 1917 was said to have killed more young farmers than did the first World War.)
Ferguson system solves problems
One solution was to mount the implement directly to the tractor. Because of the accuracy required for the resulting farming process, for a time that method became very popular for mounting row-crop cultivators. The drawback was hook-up time. The cultivator was essentially assembled onto the tractor, then disassembled to remove. It was not a quick process.
Enter Harry Ferguson, an Irish farmer’s son and mechanical visionary. Ferguson believed most implements should be connected to the tractor in such a way that although mounted to the tractor’s rear, the implement and the tractor acted as a single unit when in operation.
Because that increased overall effective length, the tipping danger was eliminated (achieving one of Ferguson’s primary goals). Likewise, the backing up and back-up steering problems were also largely eliminated.
The birth of draft control
But two problems remained: How to quickly connect and disconnect the implement, and the unstable condition resulting from the longer, overhung assemblage. This longer length adversely affected working depth control for the overhung (to the rear) implements, particularly plows. (A secondary goal for Ferguson was the elimination of weight-bearing “depth gauge” wheels on implements.)
The connection problem was simply solved by the famous Ferguson 3-point hitch system of three links with pins at both ends. By the time the Ferguson hitch was patented, hydraulics had developed sufficiently that the operator could, with the touch of a convenient lever, lift or lower the implement as desired.
But the implement depth control problem (made even more unstable due to overhung geometry and constantly changing soil conditions) continued to threaten the overall effectiveness of Ferguson’s system. Even before integration of hydraulics into the system, Ferguson conceived draft control, a system capable of sensing the varying load against the tractor’s pull, and lifting or lowering the implement to compensate.
Voilà! The result was a tractor much easier to operate effectively, and one that plowed as well or better than a tag-along, and, because it used the plow’s suck (yes, that’s the proper technical term!) to transfer plow weight to the tractor’s drive wheels for improved traction, it pulled plows as if the tractor weighed twice as much. Metal costs money, so that allowed Ferguson-designed tractors to be built lighter and less expensively, yet plow (when used with properly designed plows) as well as their heavier, more expensive competitors.
Technology that endures
A little understood and appreciated feature of Ferguson’s 3-point hitching linkage was that its linkage’s geometry effectively towed a properly attached and adjusted implement as if it were single-pin-attached to a point 6 feet, 9 inches ahead of the tractor’s rear axle. This feature, if not defeated by use of sway bars and/or improper implement adjustment, allowed the implement to swing following the tractor, thus providing the directional compensation inherent to tag-along implement attachment.
The first mass-produced tractor with the Ferguson system was the 9N/2N Ford introduced in 1939. Built by Ford to be distributed by Harry Ferguson, Inc., it was marketed from 1939 to mid-1947. Approximately 750,000 were built; how’s that for proven success?
Now that Ferguson’s patents have expired, all tractor manufacturers incorporate 3-point hitch and draft control into their tractors. Next time you pass a tractor dealership, take a look at the rear of the new tractors. You’re sure to see Harry Ferguson’s fingerprint on every one. Not bad for an innovative Irish farm boy. FC
Chuck Lyons is a graduate mechanical engineer, farm-raised in the row-crop/orchard country of Washington’s Yakima Valley. An equal opportunity tractor collector who enjoys all paint colors, he can be reached at email@example.com.
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