High-pressure hydraulics describes the generation, transmission, and use of very high hydraulic pressure to transmit force and motion in compact tools. It is the technical backbone of many mobile demolition and separation processes where controlled, quiet, and low vibration levels are required. In applications such as concrete demolition, rock splitting, building gutting, or cutting metals, high-pressure hydraulics enables high power density with good metering – essential for tools such as concrete demolition shear or stone and concrete splitting devices from Darda GmbH.
Definition: What is meant by high-pressure hydraulics
High-pressure hydraulics refers to hydraulic systems that operate with pressures typically up to about 700 bar and convert this energy via hoses, valves, and cylinders into linear or rotational work. Unlike low- or medium-pressure hydraulics, the focus here is on maximum power density in a compact design. A hydraulic power pack (pump, drive, tank, filter, valves) generates the pressure; a connected tool — such as a concrete demolition shear or a hydraulic wedge splitter — converts it into high forces. Advantages include precise controllability, repeatability, and the ability to hold loads statically without continuous energy input.
Operating principle and key components
The core of high-pressure hydraulics is Pascal’s law: pressure acts uniformly in all directions in an enclosed fluid. A pump generates pressure, and a cylinder converts it into force via the effective piston area. In demolition and splitting applications, this allows controlled clamping, crushing, cutting, or splitting with high precision and minimal vibration emissions.
Power packs and pumps
High-pressure packs (hydraulic power units) supply the operating pressure for one or more tools. Depending on the application, electric, battery-powered, or combustion-driven drives are used. Important characteristics include maximum pressure, flow rate (speed), duty cycle, cooling, and part-load behavior. For mobile demolition works, a robust, splash-proof, and temperature-stable design is relevant, especially with longer hose runs or in tunnel construction.
Cylinders, tools, and grapples
At the work site, cylinders and cutting/splitting tools convert pressure into mechanical work. Examples include stone and concrete splitting devices using a wedge system, concrete demolition shear for crushing and separating concrete with or without reinforcement, combination shears, multi cutters, a multi grapple, and steel shear for ferrous and non-ferrous materials, as well as tank cutters for cold cutting of vessels. The fine controllability of high-pressure hydraulics enables controlled load pick-up and stepwise material separation — an advantage in special demolition, building gutting, or sensitive areas.
Hoses, couplings, and distributors
High-pressure hoses transmit pressure and flow to the tool. They must be pressure- and temperature-resistant, abrasion-resistant, and kink-proof. A quick coupling enables fast coupling and decoupling without significant oil loss. Distributors and directional valves serve multi-tools or different motion directions (e.g., opening/closing a concrete demolition shear).
Valves, pressure limitation, and measurement
Pressure relief valves protect the system against overload. Check and directional valves control the flow; lowering counterbalance valves stabilize loads. Precise measuring points and pressure gauges allow monitoring of operating pressure and system condition — essential for reproducible cuts, splitting cycles, and safe load cases.
Pressure ranges, power density, and control
Typical system pressures in high-pressure hydraulics are up to about 700 bar. The attainable force results from the product of pressure and the effective area of the cylinder. Small, lightweight tools can thus exert enormous forces safely and sensitively. Proportional controls and finely tuned valve technology support gentle start and stop behavior, enabling low-crack, low-vibration operation in deconstruction.
Force transmission in splitting and shear applications
During splitting, a wedge penetrates a predrilled hole and, via the hydraulics, builds up high radial stresses. The material opens in a controlled manner along the stress path. Concrete demolition shear, by contrast, applies compressive and shear forces to the component and separates concrete from reinforcing steel or crushes components in sections. In both cases, the reproducible force development of high-pressure hydraulics is decisive for quality, safety, and progress.
Hydraulic fluid, temperature management, and filtration
The choice of hydraulic fluid affects lubrication, efficiency, temperature behavior, and seal compatibility. Common hydraulic oils with suitable viscosity support cold starts and prevent excessive heating in continuous operation. Cleanliness is critical: effective filtration and regular oil care reduce wear, extend maintenance intervals, and stabilize performance data. Temperature management — for example via cooling circuits, heat exchangers, or adapted work cycles — prevents oil aging and performance drop, especially during long operations and in enclosed spaces.
Safety, work organization, and ergonomics
High-pressure hydraulics requires careful planning, instruction, and personal protective equipment. System components must be matched, pressure limits observed, and tools used as intended. Safety aspects include, among others:
- Inspection of hoses, couplings, sealing points, and gauges before each use
- Observance of permissible operating pressure and maximum tool opening
- Securing the hazard zone, safe standing surfaces, and load-free positioning, including a proper safety distance
- Avoidance of crushing hazard and shear pinch points; controlled pressure release after work
- Protection against hydraulic fluid injection injuries and environmentally sound handling of hydraulic fluid
Legal and normative requirements vary by location, machine, and activity. In general: use only suitable, regularly tested equipment and observe manufacturer specifications for operational safety and occupational safety.
Fields of application: From concrete demolition to tunnel construction
The strengths of high-pressure hydraulics lie in controlled force deployment, precision, and mobility. This makes it suitable for different application fields:
Concrete demolition and special demolition
Concrete demolition shear and combination shears enable low-vibration selection, crushing, and removal of concrete, including handling of reinforcing steel. Stone and concrete splitting devices create targeted, low-crack separation joints — useful for partial removals, foundation exposure, or deconstruction in occupied buildings. For methods and planning guidance, see concrete demolition and deconstruction.
Interior demolition and cutting
In interior spaces, hydraulic tools excel with low emissions. Multi cutters, steel shear, and tank cutters allow material-appropriate cutting of profiles, pipes, sheets, and vessels. High-pressure hydraulics delivers the controllable force for accurate cutting steps and safe clamping in interior demolition.
Rock excavation and tunnel construction
Hydraulic wedge splitter moves rock in a controlled manner, without explosives. This is advantageous in sensitive geology, with small overburden, or near existing structures. The system can be modularly adapted to tight jobsites and sequential advance plans in tunnel construction. This aligns with rock demolition and tunnel construction practices.
Natural stone extraction
In the extraction and sizing of natural stone, hydraulic splitting devices enable dimensionally accurate blocks with clean surface quality. The process is repeatable and gentle on the material — important for yield and downstream processes in natural stone extraction.
Special operations
In special situations — such as technically complex dismantling, underwater work, or in an ATEX zone — high-pressure hydraulics allows adapted, low-spark procedures. Cold cutting with suitable tools reduces thermal effects and minimizes ignition sources.
Relation to concrete demolition shear and stone/concrete splitting devices
Concrete demolition shear and stone or concrete splitting devices are considered classic application fields for high-pressure hydraulics because they introduce high forces safely, in a metered manner, and locally confined.
Concrete demolition shear: Crushing, separating, selecting
- Opening/closing with sensitive control: controlled removal layer by layer
- Handling reinforcement: clean exposure or separation in combination with shears
- Reduced vibrations: advantageous in existing buildings, hospitals, laboratories
- Good view of the working joint: precise work on edges, slabs, and walls
Stone and concrete splitting devices: Wedge principle with high reproducibility
Pre-drilled holes take the splitting wedge; the hydraulically actuated wedge generates defined tensile stresses in the component or rock. Advantages include low noise and dust generation, a predictable crack path, and the ability to open even thick components section by section. In tunnels, inner-city projects, or heritage conservation, this method proves itself as a non-explosive alternative.
Selection and sizing: Making the system fit
- Define the task: material, component thickness, reinforcement level, desired cut or split line
- Determine force requirements: required cylinder forces or shear/splitting forces, desired cycle times
- Select the power pack: pressure, flow rate, energy supply, operating time, thermal reserve
- Match accessories: hose lengths, couplings, valves, measuring points, protective sleeves
- Consider safety and environmental conditions: noise, dust, emissions, accessibility
- Pilot run/mock-up: validate parameters, optimize operating concept and sequence
Maintenance, servicing, and troubleshooting
Regular care preserves performance and safety. Typical measures:
- Check oil condition and change at intervals; monitor filtration
- Inspect hoses and couplings for abrasion, kinks, and tightness
- Functionally test gauges, valves, and safety functions
- Inspect cylinder guides and seals; replace wear parts on schedule
- Localize performance loss systematically: suction side, filter, bypass, valve states, oil temperature
Work on high-pressure systems is carried out depressurized and after release. Documented inspections and visual checks before each use increase operational safety.
Efficiency, emissions, and sustainability
High-pressure hydraulics enables quiet, low-vibration methods with minimal secondary damage. Finely metered forces reduce rework, protect the structure and surroundings, and cut waste volumes. Electrically powered hydraulic power pack can reduce emissions indoors. Demand-based flow, short hose runs, and clean oil management increase energy efficiency and extend component service life.
Documentation, qualification, and work preparation
Sound work preparation includes selecting suitable tools, providing the operating manual, risk assessment, and operator instruction. Test records, maintenance evidence, and consistent implementation of manufacturer specifications contribute to legal certainty and equipment availability. For complex tasks in special demolition or tunnel construction, a step-by-step approach with clear communication and release paths is recommended, supported by structured work preparation and planning.