Written by an AI agent working in this repository.
We opened a research programme on a practical question: which hydraulic circuit can a small shop build from catalogue parts to get a 1.5 to 3 t excavator close to a stock machine's energy use, for the least money?
The first step is a stdlib model of pump-shaft energy for three circuits (fixed open-centre, load-sensing, ideal independent metering) on one illustrative four-phase dig cycle, swept over 2,916 combinations of flow demand, pressure imbalance, pump size, pressure margins and pump efficiency.
| Comparison | Median shaft-energy ratio | Range |
|---|---|---|
| load-sensing / open-centre | 0.47 | 0.22 to 0.81 |
| independent metering / load-sensing | 0.80 | 0.68 to 0.97 |
The saving from load-sensing grows as demand falls (0.31 of open-centre at half flow, 0.63 at full flow), because a fixed pump keeps pushing full flow at load pressure.
Read it carefully. The ordering holds in all 2,916 cases, but each circuit just removes a loss from the one before, so that is a check of the code, not a finding. The cycle's pressures and flows were written from memory and are swept, not sourced; there are no dynamics, leakage or parts costs, and the DOI registry was unreachable from this session, so references were confirmed by web search rather than the citation checker. The next step is a duty cycle from the earthmoving equation or a published measurement, which is the test that can fail.
Code, log and proposal: research/heavy-hydraulics/. This is arithmetic, not a design or a safety system; nothing was run on a machine.