Toppers: cutting the stem of the onions

TOPPERS

These are machines that cut the stem of the onion to the required length.

The "TOPPERS" are used to cut the stem of the onion to an exact measurement. In the majority of cases this is after mechanised harvesting. This is because the haulm toppers used in mechanised harvesting cut off the majority of foliage, but in an uneven manner. This leaves a fairly unappetising product.

Manual harvesting does not require a topper as the harvesters in the field cut the stems.

How do the toppers work?

A closed topper.

An open topper.

How toppers work:

1. The onions are fed into the topper by an elevator belt.
2. The onions pass over vibrating stainless steel grids, whose movement pushes the onions on through. (See photo below right)
3. Underneath this vibrating grid are well-sharpened propeller shaped knives that rotate at high speed. The stems are sucked through the grid, and the knives cut them off. (See photo below)
4. The distance between the grid and the knives determines the length of stem that will be left on the onions. This distance is easy to adjust.

For greater clarity, see the video at the bottom of this page.

The knives are easy to change.

The knives must be cleaned regularly. During use, the sugars from the onions form a hard layer on the grids and knives. Using a pre-cleaner before the topper reduces the need to sharpen the knives. The sharper the knives, the cleaner the cut.

The grids are easy to change.

When onions with thicker stems are cut, a different grid is used with more distance between the holes than those used for cutting finer onions. Each topper comes equipped with several grids. The grids must be cleaned regularly.

The inside of a topper with onions.

The yellow motors are the vibrators that move the onions.