The lift trolley
One tool moves every battery box: a low scissor lift on four casters. It rolls under the truck, the tractors or the house rack, and a hydraulic foot pump raises the deck from 100 to 600 millimetres to dock the box. No electronics. Step it through its travel, or hide the box to see the scissor.
Why a foot pump. Folded flat, a scissor starts almost level — its arms at 2.6° — so pulling it open at the rated 250 kilograms takes about 55 kilonewtons. No hand crank does that; the lever of a hydraulic foot pump does, at about 58 megapascals in a small pull cylinder, inside the pump's 70. Near the top the scissor moves almost one to one, so short strokes of the pump meter the last few millimetres the guide pins and latches need.
One tool for every dock. The same 840 × 500 mm deck and two locating pins carry a box to the electric truck, whose boxes sit 515 mm up, to the house rack at 526, to the electric straddler at 310, and to the raspberry sprayer, whose boxes ride only 155 mm off the ground. A notched lock bar and a drop pin hold the deck at any height.
Simple on purpose. Four arms of flat steel, a base on four corner casters, a handle, one cylinder and a foot pump — about 96 kilograms. It clears the floor by 8 mm: a tool for a shop floor, not a field.
What it does not show: none of it is built. The stresses in the arms and pins are hand estimates, and the first trolley is proof-loaded to one and a half times its rating — 375 kilograms — before a box goes on it. The casters, the cylinder and the pump are not yet chosen by part number.