I can’t provide a direct PDF or a link to a copyrighted copy of Industrial Hydraulic Control by Peter Rohner, as that would violate copyright law. However, I can write a useful, original article summarizing key insights from Rohner’s work, focusing on practical industrial hydraulic control principles—particularly his well-known approach to proportional valves, fault-finding, and system efficiency. Below is a technical article you can use for study, training, or reference.

Optimizing Industrial Hydraulic Systems: Lessons from Peter Rohner’s Control Philosophy Peter Rohner’s Industrial Hydraulic Control is widely regarded as a practical bridge between theoretical fluid power and real-world troubleshooting. Unlike many academic texts, Rohner emphasizes functional understanding over complex mathematics—ideal for technicians, maintenance engineers, and system designers. 1. The Core Principle: Control, Not Just Power Hydraulic systems are often seen as brute-force tools. Rohner reframes them as precision control devices . Key takeaways:

Pressure is a reaction to load – Not a setpoint to force. Flow controls speed – But only if downstream pressure is stable. Valve spool position determines flow & direction – Understanding spool metering notches is critical.

“A hydraulic system must first be stable, then efficient, then controllable.” — P. Rohner (paraphrased from multiple chapters)

2. Proportional Valve Tuning Without Oscillation Rohner provides a systematic method for tuning proportional directional and pressure valves: | Step | Action | |------|--------| | 1 | Disable all derivative action (D = 0) | | 2 | Set proportional gain (P) just below oscillation | | 3 | Increase integral gain (I) to eliminate steady-state error without overshoot | | 4 | Re-introduce derivative (D) only for fast-cycling axes | This P-I-D sequence is still taught in modern servo-hydraulics courses, but Rohner’s version includes practical valve deadband compensation. 3. Fault-Finding Matrix (Adapted from Rohner) Rohner’s fault-diagnosis charts are legendary. A simplified version: | Symptom | Likely Cause (Rohner’s order) | |--------|--------------------------------| | Cylinder drifts when valve centered | Worn spool / lands or pilot check leaking | | Slow actuation, full pump flow | Clogged pilot filter or low solenoid voltage | | Overheating oil | Relief valve partially open or wrong valve overlap | | Jerky motion at low speed | Stick-slip + too high dP across proportional valve | He stresses measure before disassembly – check pilot pressure, coil resistance, and contamination level first. 4. Efficiency Through Load-Sensing & LS Balancing Rohner dedicates significant coverage to load sensing (LS) systems, pointing out that:

LS compensators maintain a fixed ΔP (typically 20–30 bar) across the main spool. Multiple LS-actuated valves require shuttle valve networks – whichever actuator has the highest load pressure becomes the LS signal. A common mistake: using LS with fixed displacement pumps without a pressure cutoff , causing energy waste as heat.

His recommended LS tuning procedure:

Set standby pressure (lowest LS signal). Set ΔP across main spool (adjust compensator spring). Verify no LS pressure bleed through directional valves at neutral.

5. The Role of “Bad” Practices He Warns Against Rohner famously lists what not to do:

❌ Using a throttle valve before a pressure compensator (causes instability). ❌ Connecting tank lines of proportional valves directly back to pump inlet (cavitation). ❌ Mounting accumulators without proper pre-charge (reduces effective volume by >80% if pre-charge ≠ 0.9 × min system pressure).

6. A Practical Rohner-Style Exercise Problem: A hydraulic press drifts downward when the directional valve is in neutral. Rohner-based analysis:

Check pilot-operated check valve (PO check) – often the real cause. Measure load pressure – if > pilot pressure ratio × pilot pressure, PO check will crack open. Verify counterbalance valve setting (if any) – should be ≥1.3× max load-induced pressure. Only then check spool leakage.