A hay bailer is designed to turn fresh hay into bales. In general, a hay bailer uses a device called a pickup to harvest the hay. This is a series of metal bands on a spool that rotates as it passes over the hay in the field. The pickup harvests the hay and sends it into the bailer. Inside the bailer, the hay is pressed into the bale and cut to size. Some bailers press them into square bales, others into larger round bales.
A square bailer is typically a smaller machine attached to a tractor and pulled through the field. It uses large tires spaced at a distance to optimally reduce the impact on the earth. This bailer has a pickup that harvests hay and sends it into a baling device. The hay is compressed inside the bailer by a spring mechanism and packing arm that moves back and forth as hay is collected inside the chamber. It cuts the hay and packs it in the bailer. When a complete bale is made, the machine ties the bales with twine and sends them down a chute and onto the ground.
A round bailer is a larger machine that create bigger, round bales of hay. It is used for larger hay fields on horse farms and dairy farms. This machine operates differently from the square bailer, but it uses a similar pickup device. Instead of packing and cutting hay uniformly, it collects and rolls the hay into circular bales using a series of belts. These belts collect hay as it is harvested and continually wrap it into the bale. A pressure-sensing device alerts the driver as when the bale is "full." They then stop the machine. The bailer secures it with twine, and the entire bale is discharged onto the ground.