Power unit

In a technical context, a power unit is a self-contained assembly of components that together perform a function. In demolition and extraction technology, this usually refers to the hydraulic power unit (HPU): the mobile or stationary power unit that provides hydraulic energy for tools. Without a suitable power unit, concrete crushers, combination shears, steel shears, tank cutters, or stone and concrete splitters cannot deliver their effect. Especially in application areas such as concrete demolition and specialized deconstruction, strip-out and cutting, rock demolition and tunnel construction, as well as natural stone extraction, power units are the heart of the process chain – they generate pressure and flow rate, control movements, and ensure reproducible work cycles. In these contexts, Darda GmbH relies on robust, easy-to-handle hydraulic power units that are technically matched to the respective tools. Clear operating logic and compatibility with the intended attachments are essential for safe, efficient workflows.

Definition: What is meant by a power unit?

A power unit is understood as a combination of mechanical, hydraulic, or electrical components that together perform a clearly defined task. In the context of Darda GmbH, the term primarily stands for the hydraulic power unit (also called performance unit, powerpack, or drive unit, often abbreviated as HPU). It converts drive power (e.g., electric motor or combustion engine) into hydraulic energy and supplies connected tools such as concrete crushers, multi cutters, or stone splitting cylinders with pressure oil. Besides this practical meaning, “power unit” can also describe an assembly in design – for example, the complete hydraulic block including pump, tank, valves, and filters as a single unit, implemented as a single- or multi-circuit configuration depending on the application.

Design and operation of hydraulic power units

A hydraulic power unit from Darda GmbH is designed to be compact, portable, and optimized for the requirements of mobile demolition and splitting technology. It typically includes:

• Drive: Electric motor (for low-emission indoor and tunnel operation) or combustion engine (for flexible outdoor sites).
• Pump: Often gear or piston pump that generates the required pressure and flow rate.
• Hydraulic tank with oil level indicator, air filter/vent, and sufficient volume for heat dissipation.
• Filtration in suction and return line with suitable fineness to ensure oil cleanliness.
• Oil cooler and temperature monitoring for consistent viscosity and longer service life.
• Valves (control, directional, and pressure valves) including pressure relief and optional fine metering.
• Measuring and display elements such as pressure gauges, temperature, and status indicators.
• Quick couplings and hose bundles, matched to single- or double-acting operation.
• Enclosure and frame: protective frame, lifting points, and paneling for component protection and ergonomic handling.
• Sensors and connectivity: hour meter, status signaling, and fault indication for troubleshooting and documentation.

The function chain is straightforward: the drive powers the pump, oil is drawn from the tank, pressurized via valves, and routed through hoses to the tool. With a concrete crusher, the power unit controls the opening and closing of the jaws; with stone and concrete splitting devices, it supplies the cylinders that generate controlled splitting forces. Through return lines the oil flows back into the tank via filtration, and pressure relief protects the system and tool. Correctly set relief and sequence valves ensure safe transitions between approach, work, and return strokes.

Types and drive options

Which power unit variant is appropriate depends on the environment, power demand, and logistics:

• Electric hydraulic power units: Ideal for indoor areas, tunnels, or sensitive environments without exhaust and noise exposure. They require a proper power supply (e.g., site power, three-phase) and are common in strip-out and specialized deconstruction.
• Combustion engine power units: Offer maximum mobility when no electrical supply is available. Suitable for outdoor areas, rock demolition, and large deconstruction sites. Exhaust routing and noise control must be addressed organizationally.
• Battery-electric power units: Enable cable-free operation with low local emissions where grid access is limited. Useful for short, repetitive tasks and confined areas, provided that charging logistics and duty cycles are aligned.

There are also versions with different control concepts, such as simple hand/foot valves or sensitive proportional controls for tools like concrete crushers or combination shears, where cycle times and metering capability determine productivity. Start-stop and eco modes can reduce idle consumption in intermittent operation.

Performance parameters and sizing

The following parameters are decisive for sizing a power unit:

• Maximum pressure (typically several hundred bar): determines achievable force at the tool; critical for splitting and cutting tasks.
• Flow rate (L/min): affects tool movement speed and thus cycle times, e.g., closing a concrete crusher.
• Drive power (kW): must provide pressure and flow rate even under continuous load.
• Tank volume and cooling: ensure thermal stability and long oil service life.
• Duty type (duty cycle, intermittent/continuous): important for series cycles in deconstruction.
• Hydraulic oil quality and filtration: directly linked to wear, seal life, and system cleanliness.
• Acoustic emissions (sound power/pressure): relevant for work permits, shift planning, and indoor use.
• Ambient conditions (temperature, altitude, dust): influence viscosity, cooling capacity, and derating.

Splitting cylinders in stone and concrete splitting devices typically require high pressure at moderate flow rates, whereas concrete crushers and combination shears often need higher flow rates for short cycle times. Proper sizing prevents loss of performance and overheating and increases throughput on site. Viscosity index, cold-start behavior, and permissible voltage or fuel fluctuations should be factored in at the planning stage.

Interfaces to attachments and tools

Compatibility between the power unit and the tool is crucial. Relevant aspects include:

• Couplings and hose bundles: pressure- and temperature-resistant, with mix-up and leak protection.
• Single- or double-acting control circuits: matched to the tool (e.g., double-acting for concrete crushers; single-acting with return spring for certain splitting cylinders).
• Control logic: sensitive proportional control for precise cutting and gripping; defined end positions for reproducible splitting operations.
• Return-line filtration and oil cleanliness: especially important when changing tools frequently.
• Permissible back pressure and hose IDs: ensure adequate return flow without heat build-up or performance loss.
• Auxiliary functions: pressure-hold, speed-up circuits, and check valves for stable positioning and repeatable cycles.

Control and operation

Depending on the version, operation is via hand valves, controls on the power unit, or remote control elements. For delicate tasks, such as separating precast concrete elements with multi cutters or deconstruction with steel shears, fine control movements are advantageous. Clear markings for pressure and return lines, easily readable indicators, and a clear emergency stop increase process safety.

• Ergonomics: logically grouped controls with distinct haptics reduce operating errors.
• Safety functions: deadman operation and defined neutral positions prevent unintended movements.
• Labeling: durable symbols and color coding support quick identification even in low light.

Applications

Concrete demolition and specialized deconstruction

In selective deconstruction, the power unit controls the powerful yet controlled work of concrete crushers, combination shears, and tank cutters. High flow rate shortens gripping and cutting cycles; precise pressure regulation prevents material overlap and damage beyond the cut line. With load-bearing components, finely tuned hydraulics are important to minimize vibrations and secondary damage. Documented setpoints for pressure and flow support quality assurance and repeatability.

Strip-out and cutting

Interior deconstruction often requires low-emission electric power units. Low noise emissions, compact dimensions, and adequately sized oil coolers are crucial when concrete crushers or multi cutters operate in confined spaces. Hose routing, drip protection, and clean coupling changes support site hygiene and reduce downtime. Where access is limited, long hose bundles with flow-optimized diameters maintain tool dynamics without excessive pressure drop.

Rock demolition and tunnel construction

In rock removal and tunnel construction, robust hydraulic power units with high pressure levels excel for stone splitting cylinders and stone and concrete splitting devices (e.g., Rock splitters). The combination of high splitting force and repeatable cycles enables low-vibration removal – an advantage over percussive methods. In tunnels, zero emissions (with electric units) and thermal management are also key. Dust, ambient heat, and constrained ventilation require vigilant cooling and filtration strategies.

Natural stone extraction

For extracting blocks from rock, power units that provide consistently high pressures are required. A thermally stable system ensures uniform splitting joints and reproducible results. Sensitive control supports guided insertion and repositioning of the wedges on stone splitting cylinders. Robust frames and protected gauges withstand rough quarry logistics.

Special applications

In special situations – such as with sensitive structural elements, critical environments, or limited energy supply – power units are selected based on mobility, emissions profile, and control behavior. Tank cutters and steel shears benefit from stable pressure holding and clearly defined approach and return movements to achieve clean cuts and safe separation. Configurable limit pressures and clearly labeled quick-couplers contribute to predictable sequences.

Operation, safety, and work organization

Safe operation of a power unit includes technical and organizational measures:

• Setup: tip-proof, level surface; adequate air supply; weather protection as required by the version.
• Safety: emergency stop, protection against pinch points, pressure relief before uncoupling, regular visual inspection of hoses.
• Workflow: clear signals between the tool operator (e.g., concrete crusher) and the power unit operator; defined pressure and flow specifications.
• Environment: drip trays or suitable underlays to prevent oil contamination; proper disposal of operating fluids.

Legal and normative requirements can vary by country, place of use, and activity. It is advisable to observe the applicable regulations, conduct training, and provide protective equipment. Lockout-tagout procedures, documented function tests, and periodic gauge checks enhance process reliability.

Maintenance, care, and service life

The service life and availability of a power unit depend strongly on care and maintenance:

• Oil condition: regularly check level, viscosity, and cleanliness; replace filters per interval or condition monitoring.
• Tightness: inspect couplings, fittings, and hoses for leaks; replace aged lines in good time.
• Cooling: clean cooler fins; monitor temperatures under continuous load.
• Drive: inspect the motor, belts/couplings, and electrical connections; protect against moisture.
• Season and usage profile: with frequent tool changes (concrete crushers, combination shears, multi cutters), monitor coupling wear; in splitting operation monitor cylinder seal condition.
• Spare parts and consumables: keep filters, seals, and hose guards in stock to minimize downtime.

Clean documentation of maintenance tasks, operating hours, and events (e.g., temperature spikes) facilitates predictive maintenance. Oil sampling with trend analysis and targeted leak checks reduce lifecycle costs and support high availability.

Transport, setup, and power supply

Depending on size, power units are moved using carry handles, lugs, or chassis. For transport, observe weight data, lifting points, and center-of-gravity markings. On site:

• Energy supply: adequate power source for electric units (conductor cross-section, protection, power quality) or fuel management for engine-driven units.
• Hose management: route to avoid abrasion and tripping; observe bending radii; protect against sparks.
• Weather: plan for start-up times and oil preheating in cold conditions; provide shading and airflow in hot conditions.

Use suitable tie-downs and ramps, secure the unit against rolling, and verify protective devices such as residual current protection where applicable. Cable lengths, voltage drop, and harmonics should be considered for reliable operation of electric drives.

Sustainability and emissions

Hydraulic power units influence noise, exhaust, and energy consumption. Electric units operate with zero local emissions and are advantageous indoors and in tunnel construction. Efficient sizing (only as much pressure and flow rate as necessary) reduces energy demand and heat generation. Oil care, low-leak couplings, and clean handling reduce environmental impact. Regenerative or rapidly biodegradable hydraulic oils can – where technically suitable – contribute as well. Recording energy use and noise levels enables evidence-based improvements in site planning.

Selection criteria and planning

When selecting a power unit, matching it to the intended tool is crucial:

• Tool profile: concrete crushers, combination shears, and steel shears often require higher flow rates; stone and concrete splitting devices and stone splitting cylinders require higher pressure levels.
• Place of use: interiors and tunnels favor electric units; outdoor areas benefit from the autonomy of engine-driven units.
• Thermal management: sufficient cooling capacity for continuous cycles; reserves for hot summer days.
• Mobility: dimensions, mass, carrying options; hose lengths and coupling concept.
• Operation: clearly structured controls, easily readable indicators, emergency stop, quick pressure adjustment.
• Service and documentation: accessible components, clear manuals, and defined maintenance intervals.
• Compliance: conformity with applicable directives and site requirements for emissions and noise.

Reliable planning also considers reserve capacity for peak loads, the quality of the power supply, and the logistical sequence of tool changes. Standardized couplings and documented setpoints simplify commissioning and reduce errors.

Practice-oriented configurations

• Strip-out in existing buildings: electric hydraulic power unit with proportional control and moderate flow rate; concrete crusher or multi cutter for selective separation; long hose bundles with drip protection.
• Specialized deconstruction of concrete beams: high-performance power unit with high flow rate for short gripping cycles; combination shear for cutting and gripping; temperature monitoring under continuous load.
• Rock removal in tunnels: electrically driven power unit with high pressure stability; stone and concrete splitting devices and/or stone splitting cylinders; focus on cooling and ventilation.
• Natural stone extraction in the quarry: robust power unit with large tank and reliable filtration; precise pressure control for repeatable splitting joints.
• Special application at tank facilities: finely metered power unit with a clear emergency stop logic; tank cutter with defined cutting guidance; strict hose routing and spark/leak protection.
• Bridge deck or floor slab separation: electric HPU with proportional control and high flow rate for rapid jaw cycles; attention to noise constraints and power distribution on multi-level sites.

Terminology and usage

In everyday practice, “power unit” is often shorthand for the hydraulic power unit, i.e., the complete power unit supplying tools such as concrete crushers, combination shears, or steel shears. Technically, the term can also refer to other functional assemblies. In the context of Darda GmbH, the assignment is clear: it is about hydraulic power that supplies tools with pressure and flow rate, enabling controlled splitting, cutting, and gripping. Using the abbreviation HPU consistently in documentation and labels helps avoid ambiguity during planning and operation.