The Geiger Lund Selective Asparagus Harvester
Asparagus harvesters for sale.
Tractor-pull type selective mechanical asparagus
harvester.
Asparagus spears are harvested by
the header, placed on a conveyor, and transported to the rear of the
machine where a person sorts out the good spears and puts them into
boxes.
The header has four separate simple independent systems working
together to harvest the crop. The four systems are the header height
control system, the optical sensing system, the cutting system, and
the spear pickup system.
These four systems are all located on a header which can move up and
down similar to a forklift. The header is mounted on a trailer unit
that contains the air compressor, air storage tank, sorting and
packing area, and the hydraulic reservoir, motor, pump, and system
controls.
HEADER HEIGHT CONTROL
Controlling the height of the header is important
because that is what determines the length of the spears being
harvested. Over time the wheels compact the ground which in effect,
raises the height of the bed. Soil conditions, tire wear, and tire
inflation pressure also affect the height of the header above the
bed. Changing the height of the header above the bed changes the
length of spear being harvested and the depth of cut. It is
therefore important to maintain the header at constant height above
the bed.
A single hydraulic cylinder raises and lowers the header. The
cylinder is controlled by two valves. Each valve has built in speed
controls. One valve is for raising and lowering the header slowly to
keep the cutting height at 10 inches above the bed. The other valve
is for rapidly lifting and lowering the header when turning around,
and for rapidly raising the header in the case of an air cylinder
malfunction.
The header senses it’s height above the bed by dragging a thin steel
wire along the top of the bed. The wire activates either of two
non-contact inductive proximity sensors. The all stainless steel
inductive proximity switches are connected to circuitry which
controls the header’s lift cylinders’ valves. This arrangement has
proven to be extremely rugged and reliable, and it doesn’t damage
spears.
Small changes to the header height can be made by loosening the set
screws in the shaft collars at the top of the drag wire, and sliding
the wire up or down as needed.
OPTICAL SENSOR
The optical spear sensing system is a non-contact sensing system. No part of the machine touches any spear before it passes through the sensor, ensuring accurate locating of the spear for cutting.
There are no moving parts, and there is no required maintenance. The sensor has 27 optical detectors spread across the bed on 1-3/4 inch centers, and 4 lasers. The sensor will detect any spear tall enough to be harvested, down to less than 1/16 inch in diameter.
Located on the sensor are also the depth-of-stroke adjustment knob, and the cutter self-test button.
The optical detector boards are located in the lens bar, two boards behind each lens.
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