Self-Propelled Potato Harvester

Overview

A self-propelled potato harvester is a large field machine that digs potatoes out of the ridge, separates them from soil, stones, clods and haulm, and collects the clean tubers in an on-board bunker for transfer to a trailer. Unlike a trailed harvester pulled by a tractor, the self-propelled type carries its own Diesel Engine and travels on its own Chassis and Undercarriage, which gives a longer separation line, higher bunker capacity and a single operator for the whole job.

A typical 2-row machine works rows at 75-90 cm spacing, weighs 18-26 tonnes empty and is powered by a 180-260 hp turbo-diesel. Working speed in the field is 4-8 km/h, giving a throughput of roughly 1.0-2.5 hectares per hour depending on yield and soil. The whole process from share to bunker is a continuous flow, so each subsystem must be matched in speed to the one before it.

Main subsystems

The machine breaks into nine subsystems. The Diesel Powertrain holds the diesel engine, Cooling Pack and Hydrostatic Transmission. The Digging and Lifting Unit undercuts the ridge with shares. The Separation System system strips soil and trash across several sieving webs and roller tables. The Picking Table lets a crew hand-sort the flow. The Elevator and Bunker lifts and stores the crop. The Hydraulic System, Chassis and Undercarriage, Operator Cab and Electrical and Electronics subsystems power, carry, control and instrument the machine.

How it works

At the front, two Digging Share blades undercut the ridge at 100-300 mm depth. A pair of Depth Gauge Wheel gauge wheels ride the ridge top and feed back to the Depth Cylinder so digging depth stays constant as the ground rolls. Side Disc Coulter discs slice the ridge shoulders to keep the slab intact.

The lifted slab of soil and crop drops onto the Primary Sieving Web, a belt of rubber-coated steel rods. As the belt runs, eccentric Shaker Agitator Wheel agitators flex the Rod-Link Web Belt so loose soil falls through the 28-45 mm gaps between rods. A second pass over the Secondary Sieving Web removes more soil.

Trash separation follows. The Haulm Separation Unit uses spiral Haulm Roller rollers and a Finger Drag Belt to grip and eject haulm and weeds while tubers ride over. The Clod Separation Table table pairs spiked Pintle Roller rollers with Smooth Deviner Roller rollers: clods break and fall while round tubers roll forward. In stony ground the Stone Separation Unit sends dense stones across soft Cushion Roller rollers into a Stone Trap Box.

What remains passes the Picking Table, where two to six workers on the Picking Platform pull out any stragglers and drop them down a Reject Chute. Clean tubers then go up the Paddle Elevator into the Surge Bunker, a 6-9 tonne hopper with a Bunker Floor Belt moving floor. When a trailer pulls alongside, the Unloading Conveyor folds out on its Fold Cylinder cylinders and discharges from up to 4 m high.

All process drives run off the Hydraulic System system. A load-sensing Main Hydraulic Pump feeds the Proportional Valve Bank, and each Web Drive Motor sets its own web speed from the cab, so the operator can slow the flow on heavy soil or speed it up on light land. A Pressure Sensor on each circuit reports back to the Machine Control ECU.

Materials

Wear surfaces are built to survive abrasive soil. The Digging Share is boron steel and the Disc Coulter is hardened steel, both replaceable as they wear. Crop-contact parts use rubber to limit bruising: the rod web is rubber-coated, the haulm and cushion rollers are rubber over steel, and the belts are cleated rubber or PVC. The Main Frame is welded box-section steel, and the Surge Bunker is sheet steel. Bearings throughout the webs and rollers use sealed Ball Bearing units with Oil Seal protection against dust and water.

Variants

Machines range from 1-row units for small growers to 4-row high-capacity harvesters with bunkers over 15 tonnes. Bunker types split into offset-fill, even-flow and non-stop designs that unload on the move. Undercarriage choice depends on soil: wide flotation Flotation Wheel tyres at low pressure for general use, or rubber tracks for wet, heavy land where they cut compaction and rutting. Two-axle steered chassis with a rear Steering Axle keep headland turns tight.

Operation and maintenance

The operator runs the machine from the Operator Cab using the Control Joystick and the Harvest Terminal, which shows Process Camera feeds of the separators so settings can be tuned without stopping. Setup means matching web speeds and roller gaps to the soil and crop: too aggressive bruises tubers, too gentle leaves soil and trash in the bunker.

Daily maintenance is mostly cleaning and greasing. Webs, rollers and bearings are blown down and greased each day, the Cab Air Filter is checked for dust load, and the Cooling Pack is cleared with its reversing Reversing Cooling Fan. Worn shares, web rods and rubber rollers are changed as a wear schedule. Hydraulic oil and the Return Filter elements are serviced by hours, and the Fuel Filter and engine oil follow the diesel service interval.