Working pressure is the central parameter in all hydraulic tools and drives. It enables controlled splitting, cutting, and pressing of concrete, natural stone, and metals—using, for example, concrete demolition shears, stone and concrete splitters, combi shears, or steel shears from Darda GmbH. Properly understood and set, working pressure combines high performance with precise controllability, low vibration, and predictable occupational safety in applications such as concrete demolition, building gutting, rock excavation, tunnel construction, natural stone extraction, and special demolition.
Definition: What is meant by working pressure
Working pressure is the force per area acting within a system filled with hydraulic oil. It is generated by a pump in the hydraulic power pack and transmitted to the tool via hoses, valves, and cylinders. In practice, pressure is usually specified in bar, while the SI unit is Pascal. Pressure is the control variable used to set a hydraulic cylinder’s force: force equals pressure times piston area. This converts pump speed and flow rate into a targeted usable working force—for example for controlled splitting of concrete or for cutting reinforcing steel.
Physical fundamentals and units
Working pressure in a static fluid is distributed uniformly in all directions. This principle allows very high forces to be generated at the cylinder with moderate flow rates. Typical units are bar and MPa; 1 bar equals 100,000 Pa. In application, operating pressure, peak pressure, and holding force are commonly used. While peak pressure occurs briefly, the permissible operating pressure defines the continuous load on the system. Also important are the viscosity and temperature of the hydraulic oil, as they influence pressure losses in lines and valves.
Pressure generation: hydraulic power packs and components
Hydraulic power packs from Darda GmbH generate the required system pressure and provide the appropriate flow rate. Pressure generation is shaped by the following components:
- Pump (e.g., high-pressure pump) to provide pressure and flow
- Pressure relief valve to protect against impermissible peak pressures
- Control and directional valves for controlled actuation of the tools
- Hoses and couplings with burst-proof design and appropriate nominal cross-section
- Hydraulic cylinders in the tool that convert pressure into usable lifting and cutting forces
The interplay of these components determines how quickly a tool closes, which peak and holding forces occur, and how reliably the work cycle runs.
Pressure and force in tools: from principle to application
The relationship is simple: Force = pressure × piston area. In practice, additional factors such as friction, seal condition, and flow losses come into play. Examples:
- Concrete demolition shears: Pressure determines the closing force at the cutting edges. Sufficient system pressure enables severing reinforcement and controlled dismantling of components during concrete demolition and building gutting.
- Stone and concrete splitters as well as stone splitting cylinders: Here, pressure is converted into high, surface-introduced splitting forces—low in vibration and with minimal secondary damage, which is advantageous in special deconstruction and tunnel construction.
- Combi shears, multi cutters, steel shears, tank cutters: Cutting and pressing tasks benefit from a stable pressure level and well-matched flow rate to perform separations reproducibly and without unnecessary load spikes.
Typical influencing factors on working pressure
- Temperature: Higher oil temperatures lower viscosity, reduce flow resistance, and influence achievable peak pressures.
- Line cross-section and length: Cross-sections that are too small increase pressure losses; cross-sections that are too large slow actuation at the same flow rate.
- Valve and throttle settings: Sensitive control avoids pressure spikes and improves workpiece quality, for example during precise separation of components.
- Seal condition: Worn seals cause internal leakage and thus pressure drop under load.
- Oil quality: Contamination promotes valve sticking, increases friction, and reduces the effective force at the tool.
Working pressure across application areas
Concrete demolition and special deconstruction
When dismantling load-bearing components, a stable working pressure enables controlled fractures and clean cut edges. Concrete demolition shears operate efficiently when system pressure is applied reproducibly and maintained over the stroke. For massive components, an appropriate pressure range combined with sufficient piston area is crucial.
Building gutting and cutting
In building gutting, metered pressure is more important than brief peaks. A finely regulated power pack prevents material overload and reduces rework. Multi cutters and combi shears benefit from proportional pressure control to separate various material thicknesses cleanly in a single pass.
Rock excavation and tunnel construction
Stone and concrete splitters as well as stone splitting cylinders convert working pressure into splitting forces that eliminate the need for blasting. This produces low vibration and protects the surroundings. A constant working pressure and uniform flow rate are prerequisites for controlled crack formation in the rock.
Natural stone extraction
When loosening natural stone, the pressure ramp is important: a gentle pressure increase up to the splitting load minimizes uncontrolled fractures and improves block quality. Temperature-stable oils ensure consistent splitting performance over longer cycles.
Special demolition
In hard-to-access areas, compact hose routing and pressure matched to the workspace are advantageous. Pressure-reduced starts followed by a power increase improve control, for example during precise cutting on sensitive structures.
Control and regulation of working pressure
Reliable pressure control combines protection and precision. Key building blocks are:
- Pressure relief valves for system safety protection
- Pressure-reducing valves for local pressure levels at individual tools
- Proportional and directional valves for sensitive motion control
- Pressure gauges and sensors for continuous pressure monitoring
For recurring tasks, such as repeated cuts with concrete demolition shears, a defined pressure ramp increases reproducibility and reduces component stresses.
Measurement, testing, and documentation
Pressure is typically measured at the power pack and, if necessary, additionally at the tool. Good practice includes:
- Visual inspection of lines, couplings, and sealing points
- Connection of calibrated pressure gauges or electronic sensors
- Load testing with a defined work cycle
- Documentation of operating and peak pressure as well as oil temperature
Regular tests increase operational safety and help detect performance losses at an early stage.
Fault patterns with working pressure and causes
- Pressure drops under load: Indicates internal leakage in the cylinder or valves; clogged filters or low oil level are also possible.
- Unstable pressure profile: Air in the system, pump cavitation, unsuitable throttle setting, or overheated oil.
- Excessive peak pressures: Incorrectly set pressure relief valve or blocked lines.
- Slow actuation: Flow rate too low, lines too narrow, or increasing friction due to aged oil.
Safety in handling working pressure
Hydraulic systems store energy. Safe work requires that systems be depressurized before coupling or disconnecting lines, residual pressure be released in a controlled manner, and only hoses with suitable pressure resistance be used. Personal protective equipment, burst protection for lines, and clearly defined work areas reduce risks. Observe the manufacturer’s instructions from Darda GmbH; general safety rules and relevant standards serve as a guide.
Influence of medium and temperature
Hydraulic oil determines pressure behavior via its viscosity and lubricity. Oil that is too cold promotes pressure losses due to increased flow resistance; oil that is too warm reduces damping and can stress seals. Temperature-controlled operation and appropriate oil grades increase the stability of the pressure level, which is particularly relevant during long operations with concrete demolition shears or stone splitting cylinders.
Energy efficiency: balancing pressure level and flow rate
Efficient systems keep the pressure level as low as possible and as high as necessary. An application-dependent pressure adjustment is practical: coarse positioning at lower pressure, followed by work at operating pressure. This reduces heat losses, protects oil and components, and ensures uniform results in recurring cutting and splitting processes.
Selection of power pack, lines, and tool
For a coherent workflow, power pack output, hose dimensioning, valve technology, and tool must fit together. With concrete demolition shears, the balance of maximum working pressure, piston area, and cutting kinematics is decisive. Stone and concrete splitters require sufficient pressure reserve to safely exceed the splitting load without producing unnecessary peak pressures. Pay attention to coupling technology and tightness to minimize pressure losses.
Practice-oriented tips for consistent results
- Increase working pressure step by step to observe material reactions
- Keep oil temperature within the target range to ensure viscosity and pressure stability
- Bleed regularly to prevent cavitation and pressure fluctuations
- Check hoses for abrasion points and minimum bend radii
- Inspect cutting and splitting tips regularly to avoid load spikes caused by dull edges
Maintenance and servicing
Predictive maintenance stabilizes the pressure level and reduces downtime:
- Check oil condition and replace according to specifications
- Monitor filters and replace in good time
- Inspect seals and guides on the tool
- Calibrate pressure gauges and sensors
- Clean couplings and check for tightness
Consistent maintenance quality has a direct impact on the reliability of hydraulic components and the reproducibility of cutting and splitting results.