A three-point hitch provides a safe way to connect a tractor to an implement. It is designed to avoid accidents caused when an implement encounters something that restricts forward movement. Using a single-point hitch, the tractor can flip over backward as its large rear wheels continue to turn when forward motion is restricted. The three-point hitch solves this by replacing the single attachment point with three attachment points arranged in an A-frame shape.
Two points at the bottom of the "A" provide stability and height control. The top point is forced forward when the implement encounters something that restricts forward motion. This causes forward pressure to be transferred to the tractor above its centre of gravity. As a result, the tractor will tend to spin its rear wheels instead of flipping over.
Before Irishman Henry G. "Harry" Ferguson took an interest in tractors and ploughs, farm implements were generally towed behind a tractor just as they had been towed behind oxen and horses in earlier times. One of Ferguson's first contributions to farming was a "Duplex" hitch system patented in 1925. This allowed an implement to be mounted directly on a tractor equipped with hydraulically controlled height adjustment.
Hydraulic control of tractor-mounted hitch arms paved the way for adding the third hitch point critical to safe operation of a light weight, efficient tractor. His "three point linkage" was patented in 1928. It has since been standardised and is used worldwide.
The key to safe operation lies in correctly attaching the implement to the tractor and using it as intended. Start by aligning the tractor with the implement. Improper alignment will make connecting the two difficult if not impossible. You may need a "spotter" to help you back the tractor so that the bottom linkage arms are at the correct position and height to make a connection. Never allow a spotter to stand between the tractor and an implement.
When properly aligned with the implement, turn off the tractor and set the brakes before making the connection. You can manually move the linkage arms to make minor adjustments needed so that the connector pin slides easily through the arm and hitch point. Use security clips or cottar pins to hold the connector pins in place.
Restart the tractor and raise the bottom arms so that the top hitch point is properly aligned for connection. Again, shut off the tractor with the brakes set before making the final connection. The length of the top link is adjustable, allowing you to position it as needed to insert and secure the connector pin.
If the implement is "wheel powered" and without lights you are ready to go. If a Power Take Off unit, hydraulics or electricity is needed, follow manufacturer's instructions to complete the connection.