How a potato harvester works

How Does A Potato Harvester Work?

Potato harvesters are a great way to save manual labour during potato harvest. Before the invention of the potato harvester, most people dug their potatoes from the ground using a fork or a spade. Then they lifted the potatoes from the ground and placed them into a basket before tipping them into a hessian cloth bag to be stored.

Potatoes are usually grown in drills or beds, this helps the harvester dig an even width of soil and potatoes as it moves along the field. The wheels of the tractor and harvester are set at specific widths so they travel between the rows and not on top of them.

So how does a potato harvester work?

The intake share

A potato harvester has a blade where it meets the potatoes in the soil known as a share. As the harvester moves forward into crop the potatoes and soil move over the top of the share and onto a moving belt made up of equally spaced steel bars known as a web.

a potato harvester share
The share is the front of the harvester. The spade design is smooth and shiny which helps the soil and potatoes slide over it onto the web.

The main web

As the potatoes and soil travel up the web, small adjustable wheels known as agitators gently or vigorously (depending on the user settings) hit underneath the web belt. This agitation shakes the loose soil traveling on the web and makes it fall through the bars onto the ground, leaving behind only the potatoes.

main web of two row harvester unloading into boxes
Looking at the main web as the potatoes and soil travel up it. This is a non- bunker two-row harvester – it needs a trailer to unload into as it harvests.

Haulm roller and fingers

When the potatoes reach the top of the 1st separation web there is usually a series of weighted metal bars pointing downward. These bars are known as haulm fingers and they direct any potato tops (haulm) into a rubber-coated haulm roller turning in the opposite direction to the main web roller. This causes the haulm to be pulled from the harvester and onto the ground below.

Haulm fingers positioned at the top of the main web (right). The rubber roller underneath is the haulm roller. 2nd web is to the left.

Separator unit

After the first main web, there is usually another smaller 2nd web or a separator unit to further remove more stubborn soil/ stones from the potatoes.

separator unit Dahlman rollers
Rubber-covered rollers with spiral designs rotate towards each other- known as Dahlman rollers. Very effective at removing a lot of soil, stones, and green material.

Picking table

After the 2nd web or separator unit, the potatoes will either be transported off the harvester or will travel over a manned picking table first. This picking table is a web with tightly spaced bars moving slowly to enable people to pick any further clods of soil, grass, stones, or damaged potatoes out of the crop.

picking table on potato harvester
Picking table on a two-row harvester.

Unloading elevator/ bunker bin

Potato harvesters can come in many different setups of webs, separator types, picking tables, or unmanned. To unload the crop they typically only have two options – with or without a bunker. Harvesters that have a bunker to hold the potatoes can continue to harvest without the need for another tractor and trailer to drive alongside to collect the potatoes.

Grimme bunker harvester
A Grimme two-row bunker harvester – a very large heavy machine. Fewer tractors are needed to harvest but dryer soil conditions are essential.

Bunker harvesters are typically much larger and heavier and although they can harvest without the need to side fill into another tractor and trailer their weight can cause issues getting bogged in wetter fields. Remember that potatoes are usually not ready to harvest until autumn when the land is not as dry, bunker harvesters are typically used in dryer land/climates.

Fall breaker

The fall breaker is the final part of the harvester where the potatoes are transferred from the harvester to the unloading trailer. The fall breaker is a rubber-coated canvas funnel that has many strong but soft straps positioned in layers below each other.

As the potatoes fall from the unloading elevator into the fall breaker they are caught and then released in the straps. This breaks the potatoes fall from the elevator into the trailer or box. If the fall breaker was not there the potatoes would get bruised and damaged as they are dropped from a great height with nothing to break their fall. Fall breakers are fitted to all types of potato harvesters.

a potato harvester fall breaker
Notice the layers of straps inside the fall breaker to slow down the potatoes fall into the awaiting trailer or box.

I hope you found this helpful, get in touch if you have any other questions.

further reading:

https://amzn.to/3nYdXR5 – Potato Harvester (21st Century Basic Skills Library: Welcome to the Farm)

https://www.grimme.com/ie/news/grimme-50-jahre-selbstfahrtechnik.442.html