The raspberry tug and sprayer in 3D
Tractor 2 is a narrow electric tug that tows a small sprayer between the red raspberry rows, where the alley is four feet wide in spring. The tug is 42.7 inches across, steers like a zero-turn mower, and carries two battery boxes low down its middle. The sprayer trailer is 42 inches wide with its booms in: a 100-gallon tank low over one axle, the same pump and controls as the straddler, and a vertical boom each side that stands up along the canes. Swing the trailer through a headland turn, or slide the booms out for the wider black raspberry rows. A design in progress — nothing is built.
Why a tug that tows. The red raspberries end on eight-foot rows, and the canes leave a four-foot alley in spring. A machine that narrow cannot carry a big tank high without tipping, and the patch needs only a few dozen gallons per spraying. So the tug stays light and low, and the tank rides behind it on its own axle, low between its wheels.
The tug. Two free casters in front, two drive wheels behind, each with its own motor — it turns by driving one wheel faster than the other, like a zero-turn mower. The two battery boxes lie end to end on the centreline, 342 mm off the ground, and the lift trolley rolls in from either side to change them. That side access is what sets its 2.56 m wheelbase. On narrow tyres and a 920 mm track it is the least stable Drumlin machine: about 35° of sideways tilt before it tips, standing still. Side slopes want care.
The sprayer. Copied from the vertical-boom trailers berry growers already use: four nozzles a side up to about two metres, facing the canes. For the red rows the booms stay in; for the black raspberries on sixteen-foot rows they slide out 250 mm a side. A small blower is drawn as an option only — too much air damages canes.
The clearance check swung the trailer 60° each way on the hitch, turned the casters through 90° and ran the booms out. No part passes through another. What it does not show: a hitch that lets the trailer roll over uneven ground, how free casters behave with a trailer pushing downhill, and the spray coverage. The canopy width it was sized to is a measurement from the patch; the masses are estimates.