The primary use of a pendulum spreader is to apply fertiliser accurately at medium to low rates.
Pendulum-action spreaders overcome those problems.
Pendulum-action spreaders do not have a rotating impeller. They have a steel or plastic tube that sticks out horizontally behind the spreader and oscillates from side to side in a horizontal plane. Fertiliser is metered into the front of the tube using conventional metering ports, it is then slung out the end of the tube as the tube oscillates. A deflector on the end of the tube helps scatter the granules. Pendulum-action spreaders were developed in The Netherlands.
Rotary spreaders tend to skew the pattern to one side or the other and change pattern skewing with different products. Pendulum-action spreaders deliver a pattern that is generally balanced from side to side with minimal skewing. Testing of a pendulum spreader should ideally achieve results that show less than 5% skewing. Often the skewing is less than 2%. This is far better than uncorrected rotary spreader patterns. Furthermore, the patterns from a pendulum spreader tend to be symmetrical as well as numerically balanced, making it easier to find a swath width that will provide good uniformity. Swath width will vary with product, so pattern testing is still needed for each product, but the testing is much easier since it is not necessary to do repetitive testing to find a centered pattern.
Some pendulum spreaders allow you to reduce the arc of oscillation, allowing you to narrow the pattern if desired. An interesting option with pendulum spreaders is the ability to apply bands of fertiliser. If you use a tube without a deflector on the end, the fertiliser (or other granules) will be thrown in a discrete band on each side of the spreader with none in the centre of the pattern. By varying tube length, PTO speed and spout height, the spacing between the bands can be varied from about 6 metres down to less than 3 metres . This banding is handy for treating rows of trees or shrubs.
There are many brands of pendulum-action spreaders on the market, but most are manufactured by only a few companies. Many are imported from The Netherlands or Italy. Most do a decent job of distributing granules, but there is a difference in rate control on different brands. The best machines incorporate a turnbuckle-type device that allows fine setting increments, even at low rates. Some other brands have a series of holes through which a pin is inserted to form a stop for the on-off lever. These units typically have large setting increments, especially at low settings. If, for instance, you want to apply 200 kilograms to a hectare , you might find that one setting delivers 150 kilograms to the hectare and the next setting delivers 250 kilograms. The turnbuckle system gives much finer increments and is strongly recommended.
In summary, a pendulum-action spreader is usually the best choice for a tractor-mounted spreader for orchards, vineyards and turf growing. It will do everything a rotary spreader will do and generally do it better.
