The hydraulic pump is the heart of mobile and stationary hydraulic systems. It converts mechanical drive power into hydraulic energy and supplies tools such as concrete demolition shears, Rock splitters, or steel shears with the necessary flow rate and operating pressure. In combination with Hydraulic power units from Darda, the pump largely determines how quickly and powerfully a tool responds—whether in concrete demolition, building gutting, rock excavation, tunnel construction, natural stone extraction, or special demolition with particular safety requirements.
Definition: What is meant by a hydraulic pump
A hydraulic pump is a positive displacement machine that delivers a defined volume of fluid per revolution and thereby generates a flow rate. In closed hydraulic circuits, this produces—against the resistance of the connected tool—an operating pressure. For mobile demolition tools, almost exclusively displacement pumps (e.g., gear, axial piston, and radial piston pumps) are used, as they operate reliably in the high-pressure range and allow precise metering.
Design, operating principle, and types
Hydraulic pumps work on the principle of volumetric displacement: a changing working chamber takes in oil and transports it toward the pressure port. Sealing lines, clearances, and bearing quality are decisive because they influence volumetric efficiency and service life.
Typical types in demolition and splitting technology
- Gear pump: robust, compact, insensitive to contamination; frequently used in mobile hydraulic power packs for concrete demolition shears and rock and concrete splitters. A good choice when pressure and speed levels are constant.
- Axial piston pump: high efficiency, often with adjustable displacement; suitable when changing load conditions require rapid adaptation, for example with combination shears or multi cutters.
- Radial piston pump: very high pressure possible, precise behavior in the high-pressure range; predestined for applications with high splitting or cutting force requirements.
Two-stage pumps and load changes
Two-stage delivery has proven itself for mobile power packs: high flow at low pressure for rapid approach, automatic changeover to low flow at high pressure for the actual cutting or splitting operation. This behavior increases the cycle performance of concrete demolition shears and efficiently achieves the splitting force with rock and concrete splitters.
Performance data and practical sizing
The correct sizing of the hydraulic pump is a balance of flow, pressure, power demand, and thermal reserve. The following parameters are decisive in practice:
- Flow (l/min): determines tool speed (approach, cutting, splitting, return). For concrete demolition shears, a higher flow rate directly yields shorter cycle times.
- Operating pressure (bar): influences the achievable cutting or splitting force. Rock and concrete splitters require a high pressure level depending on material strength to reliably initiate cracks.
- Power demand (kW): results from pressure and flow and must harmonize with the drive of the hydraulic power pack.
- Viscosity and oil temperature: a suitable HLP oil and a controlled temperature range ensure lubrication, tightness, and efficiency.
- Intermittent duty (ED): mobile demolition work often runs in cycles; the pump must withstand peak loads without overheating.
- Noise behavior: relevant for building gutting and special demolition, for example in sensitive areas with strict noise limits.
Hydraulic pump in the system: interaction with hydraulic power packs
In the hydraulic power pack, the pump is combined with drive, tank, filter, cooler, valves, and safety components into a compact system. Power is delivered to the tool via hydraulic hose lines and couplings. Essential system aspects:
- Pressure limitation: pressure relief valves protect the pump, hoses, and tool.
- Control: directional control valves (e.g., hand lever or electrically actuated) route flow or enable return.
- Cooling and filtration: keep oil temperature and cleanliness within a range that minimizes wear and increases the pump’s service life.
- Quick coupling: reduces downtime during tool changes, important on changing construction sites.
Use with concrete demolition shears as well as rock and concrete splitters
Concrete demolition shears require rapid material contact and high force peaks during cutting/pressing, while rock and concrete splitters require targeted force transmission to initiate cracks. The hydraulic pump shapes each working behavior.
Typical sequence with concrete demolition shears
- Approach of the shear with high flow at moderate pressure for fast positioning.
- Automatic pressure buildup, reduced flow at increased pressure for the actual shearing operation.
- Return with sufficient flow to minimize cycle time.
Typical sequence with rock and concrete splitters
- Positioning in the borehole or on the intended splitting line, the pump delivers quickly.
- Pressure phase: high pressure, stable flow; the system must be pressure-stiff and temperature-stable.
- Pressure holding until breakthrough, then controlled pressure reduction and return.
Fields of application: from concrete demolition to special operations
Concrete demolition and specialized deconstruction
Here, controlled force deployment with low vibration levels at the edge is what counts in concrete demolition and specialized deconstruction. The pump must deliver short cycle times and consistent pressure peaks so that concrete demolition shears and combination shears reliably engage reinforcement and concrete cross-sections.
Building gutting and cutting
In existing buildings, noise emission, zero exhaust (for indoor operation), and low leakage are decisive. Electrically driven power packs with appropriately sized pumps offer advantages indoors. Multi cutters and steel shears benefit from a precisely metered flow rate.
Rock excavation and tunnel construction
Rock splitting cylinders require high pressure levels and pressure-stiff systems. The pump should provide high efficiency in the high-pressure range and be robust against temperature and load changes in harsh environments.
Natural stone extraction
Repeatable provision of pressure and flow is important for reproducible splitting results. Long hose lines can increase pressure losses; pump sizing must take this into account.
Special operations
Where there are special requirements—such as limited access, specific safety rules, or sensitive surroundings—compact power packs with quiet, efficient pumps have advantages. Short setup times and reliable pressure control are decisive here.
Operation, maintenance, and service life
- Oil quality: use suitable hydraulic oils (e.g., HLP) with appropriate viscosity and additives; keep the oil clean.
- Filtration: monitor filter condition; observe differential pressure indicators and replace in time.
- Cold start: at low temperatures start under reduced load to avoid cavitation and seal damage.
- Tightness: regularly check couplings and hoses; correct leaks immediately.
- Service intervals: define according to intensity of use and environment; check oil condition (particles, water content).
Safety and environmental protection
- Operate only within the specified pressure and temperature limits; do not bypass safety and shutdown functions.
- Use hose-rupture and pressure-holding functions when required by the tool, for example for overhead work or in confined areas.
- Avoid oil mist and leakage; keep suitable containment media ready, especially indoors and in sensitive areas.
- Noise reduction through appropriate speed selection, damping, and low-vibration installation.
Legal requirements may vary by location; compliance with applicable safety and environmental regulations should always be verified.
Typical fault patterns and diagnosis
- Pressure drops: possible causes are leaks, worn pump elements, defective pressure relief valve, or clogged filters.
- Excessive heating: internal leakage too high, insufficient cooling, or incorrect viscosity; check oil condition.
- Cavitation / noise: suction issues, excessive speed, restricted lines, or low oil level.
- Unstable running: air ingress, unsuitable viscosity, defective coupling, or damaged bearings.
Energy efficiency and control
Efficiency results from proper sizing, demand-based control, and low losses. The following have proven effective in practice:
- Two-stage pump characteristic: fast during idle travel, powerful during the working stroke.
- Pressure shutoff: automatic unloading after reaching the target value reduces heat generation.
- Demand-based speed: adapted drive speed lowers noise and energy consumption, especially in partial-load operation.
Compatibility with tools from Darda GmbH
Hydraulic pumps must match the hydraulic demand of the respective tool. Examples:
- Concrete demolition shears: brisk flow for shorter cycles, along with stable high-pressure behavior for the required cutting force.
- Rock and concrete splitters or rock splitting cylinders: high operating pressure, pressure-stiff system, reliable in sustained pressure holding.
- Combination shears, multi cutters, steel shears, tank cutters: a balanced compromise between flow and pressure; sensitive control supports precise cuts and controlled separation.
Selection checklist for the right hydraulic pump
- Required tool data: maximum pressure, recommended flow, cycle times.
- Drive power of the hydraulic power pack and available energy source (electric or combustion engine, indoor or outdoor use).
- Thermal reserve: cooling and oil volume in relation to duty cycle and ambient temperature.
- Hose lengths and line cross-sections: consider pressure losses and starting behavior.
- Noise and emissions requirements at the place of use.
- Service accessibility, filtration, and oil quality.
Transport and storage in mobile use
- Transport pump/power pack tip-proof; close hoses cleanly without kinks.
- Protect from weather; avoid moisture and dust to prevent corrosion and contamination.
- Before recommissioning, visually inspect for damage and tightness; check oil level.
Practice-oriented notes on system tuning
- For fast sequences with concrete demolition shears, prioritize flow without falling below the required pressure range.
- For rock and concrete splitters, the focus is on high pressure and a pressure-stiff setup; a two-stage pump characteristic can still accelerate the process.
- With changing tools, a pump with a sufficiently wide operating window and robustly sized cooling is advantageous.
Quality features and durability
Precise manufacturing, high-quality sealing systems, suitable materials, and a clean assembly environment increase the service life of a hydraulic pump. Regular condition monitoring—such as oil and filter analysis—prevents failures and preserves overall system performance in concrete demolition, building gutting, rock excavation, tunnel construction, natural stone extraction, and special operations.