Oil supply

The oil supply is the functional heart of hydraulically powered tools in demolition and extraction. It converts the energy provided by the hydraulic power pack into controlled motion and force – for example, when precisely closing concrete demolition shears or when hydraulic rock and concrete splitters work with high power. A stable, clean, and properly engineered oil supply increases performance, operational safety, and component service life, while mismatches can lead to loss of performance, overheating, and premature wear. Consistent parameter matching, contamination control, and temperature management underpin repeatable cycle times and uptime in demanding duty cycles.

Definition: What is meant by the oil supply?

The oil supply is understood as the interaction of hydraulic fluid, tank, pump, valve technology, filtration, hydraulic hose lines, couplings, and cooling that provides the required pressure and flow rate for hydraulic tools. The oil simultaneously acts as an energy carrier, lubricant, sealing medium, and heat transfer medium. In practice, the oil supply includes all measures for providing, conditioning, routing, and monitoring the hydraulic fluid – from suction in the tank and pressure generation in the power pack to return to the tank.

• Energy transfer: Converts shaft power into hydraulic power and onward into mechanical work.
• Lubrication and wear protection: Maintains film strength in pumps, valves, and actuators.
• Sealing: Reduces internal leakage at clearances and interfaces.
• Heat removal: Transports and dissipates friction and throttling heat.

Operating principle of the hydraulic oil supply

The pump in the hydraulic power pack – often part of dedicated Hydraulic Power Units – draws oil from the tank and delivers it through valves and lines to the consumer. At the tool – e.g., with concrete demolition shears, hydraulic demolition shears, Multi Cutters, or a Tank Cutter – a cylinder or motor converts pressure into mechanical work. The oil then flows back to the tank via the return line, filter, and, if applicable, cooler. Open circuits with load-independent or load-sensing control are common; they must match the tool and task to keep throttling losses and heating low. In practice, pressure limiting ensures overload protection, while correct suction conditions and venting prevent cavitation and erratic motion.

Components of the oil supply at a glance

• Hydraulic power packs: Energy source with tank, pump, drive (electric or combustion engine), valve block, and overpressure protection.
• Pumps: Fixed or variable displacement; decisive for delivery flow, starting behavior, and efficiency.
• Valves: Directional, pressure, flow control, and check functions for safe, sensitive control.
• Filters: Protection against wear caused by particles; often in suction, pressure, and return circuits.
• Oil coolers: Heat dissipation for constant oil temperature and viscosity.
• Lines and hoses: Sized to pressure, flow rate, and length to limit pressure losses.
• Quick couplings: Clean, mix-up-proof connecting and disconnecting; protective caps and cleanliness management are essential.
• Measurement and monitoring points: Pressure gauges, temperature and contamination indicators, as well as oil condition checks.
• Tank breathers and dehumidification: Moisture control to curb corrosion and oil aging.

Reservoir baffling, sufficient oil volume, and optimized return routing support deaeration and thermal balance; clear labeling of ports and coupling assignments prevents misconnections in multi-tool setups.

Oil quality, viscosity, and additives

The choice of hydraulic fluid affects cold-start behavior, power transmission, seal compatibility, and service life. Proven options include high-load hydraulic oils with wear protection (e.g., HLP) and temperature-stable variants (e.g., HV). In sensitive environments, rapidly biodegradable oils are used. Viscosity (typically ISO VG 32 or 46 for mobile applications) depends on ambient temperature, tool requirements, and cooling conditions. Also important are oxidation stability, shear stability, good air release, low foaming, and water separation. Use only approved oils that are compatible with the seals and specifications of Darda GmbH.

• Viscosity index and pour point: Support stable behavior across seasons and cold starts.
• Additive technology: AW and EP packages (zinc-containing or ashless) tuned to pump and valve materials.
• Base oil type: Mineral, synthetic, or rapidly biodegradable fluids depending on task and environmental requirements.
• Compatibility: Verified interaction with elastomers, paints, and coatings used in the system.

Sizing of the flow rate and working pressure

Flow rate determines speed; pressure determines force. Concrete demolition shears require high pressure to reliably separate reinforcement and concrete. Rock and concrete splitters and rock splitting cylinders release controlled splitting forces at high pressure. The hydraulic power pack must provide sufficient flow at stable pressure without generating excessive throttling losses. Too-small hose IDs, long line runs, or unsuitable valves lead to pressure drop and heating. A coherent design ensures repeatable cycle times and consistent tool stroke.

• Principle: Actuator speed is proportional to flow; cutting or splitting force is proportional to pressure and effective area.
• Design tips: Allow margin for peak demand; limit total pressure drop in lines and components; match valve nominal size to actual flow.
• Return side: Ensure generous cross-sections to avoid backpressure and unintended force reduction.

High-pressure ranges in practice

With steel shears, tank cutters, or Multi Cutters, dynamic load changes occur. The oil supply system must absorb pressure spikes, safely hold the tool, and avoid return-side restrictions. Pressure limiting, leakage-oil-capable concepts, and well-designed return lines ensure smooth operation. Where appropriate, accumulators and pilot-operated check or counterbalance functions stabilize motion and protect against shock loads.

Temperature management and cooling

Hydraulic fluid operates within a recommended temperature window. Oil that is too cold hampers startup and increases pressure losses; oil that is too hot reduces viscosity and lubricant film stability. Measures include demand-based cooling, avoiding unnecessary throttling losses, adequate idle times, and, if necessary, preheating in cold conditions. Seasonal viscosity selection and clean coolers improve stability – especially important under continuous load as can occur in concrete demolition and special demolition.

• Target window: Typical operating oil temperatures are approximately 40 to 60 °C; avoid sustained operation below 15 °C or above 80 °C.
• Cooling capacity: Size for peak load; keep cooler fins and oil-to-air passages clean.
• Start-up strategy: Gentle warm-up cycles reduce stress on pumps, seals, and couplings.

Filtration and cleanliness classes

Clean oil is the best life insurance for pumps, valves, and cylinders. Particles cause wear, internal leakage, and malfunctions. A well-matched filtration strategy protects the system: suction protection (coarse screening), pressure filters (fine protection for sensitive components), and return filters (system cleanliness). In addition, offline filter units, oil condition checks, and consistent cleanliness during the coupling process help. New or long lines should be flushed. Target cleanliness can be guided by ISO 4406 codes appropriate to component sensitivity; high Beta-ratio elements and water control (low saturation) extend service life.

Typical filtration concepts

• Suction-side protection: Coarse rating to avoid cavitation.
• Pressure filter: Fine filtration to protect valves and actuators.
• Return filter: System-wide particle control before tank entry.
• Offline or bypass filter: Continuous fine filtration and water binding.
• Filling filtration: Pre-filter top-up oil to prevent introducing dirt into the reservoir.

Lines, hoses, and quick couplings

Hose inner diameter, bend radii, and line lengths influence pressure losses and heating. Quick couplings must match the flow rate and be kept clean. Protective plugs, wipe-down methods, and clear assignment (color or shape coding) reduce the risk of mix-ups. With frequent coupling – such as when switching between concrete demolition shears and hydraulic demolition shears – well-thought-out coupling management prevents air ingress and dirt.

• Flow velocity guidance: Suction 0.5 to 1.5 m/s, return 1 to 3 m/s, pressure 4 to 6 m/s, case drain below 1 m/s.
• Bend radius: Observe minimum bend radii and protect against abrasion and pinch points.
• Return backpressure: Avoid undersized couplings and long narrow runs that elevate return-side pressure.

Valve technology and holding functions

Depending on the tool, single- or double-acting circuits are required. Concrete demolition shears benefit from holding or load-holding valves that reliably store pressure and prevent settling. For rock and concrete splitters, the control must initiate the splitting process reproducibly and keep the pressure side stable. Overcenter or counterbalance arrangements can add stability where overrunning loads or shock events occur.

Maintenance, operation, and oil changes

Regular checks include oil level, leaks, temperature, and operating noises. Filter changes based on indicator or interval, oil changes per manufacturer specifications, and oil sampling for condition assessment are proven measures. Tank breathers reduce moisture ingress; dry storage of reserve oil preserves quality. After longer downtimes, an orderly restart with venting is recommended. Trend-based oil analysis (particle count, water content, TAN) enables predictive maintenance and avoids unplanned downtime.

Start and stop procedures

1. Before start: Clean couplings, connect correctly, check oil level.
2. Start gently and listen for unusual noises; vent systems if necessary.
3. Warm up by cycling actuators under low load until oil reaches the target temperature range.
4. In operation: Monitor temperature and pressure; avoid throttling losses.
5. Before disconnecting: Depressurize, close and protect couplings.

Typical faults and diagnostics

• Loss of performance or slow movement: Often due to air in the system, clogged filters, or pressure losses from undersized lines.
• Jerking, cavitation, noises: Possibly unfavorable suction, viscosity too high in cold conditions, or contaminated screens.
• Overheating: Throttling losses, incorrect flow rate, insufficient cooling capacity, or dirty coolers.
• Foam and milky oil: Air or water ingress; check seals and tank breather, analyze oil condition.
• Drift or creeping: Check load-holding valves and internal leakage in cylinders or valves.
• High return-line pressure: Inspect quick couplings, hose ID, and return filter bypass status.

Relation to concrete demolition shears and rock and concrete splitters

Concrete demolition shears require an oil supply that combines constant pressure with sensitive controllability. This keeps cutting and pressing forces reproducible, even with reinforcement and varying cross-sections. Pressure-holding functions prevent unintentional opening and promote clean cut surfaces. Rock and concrete splitters need short, powerful pressure rises and a controlled retraction. Here, a suitable return cross-section, vented lines, and a stable pump characteristic have a direct effect on splitting quality and cycle times. In both cases, contamination control at the coupling interface and thermal stability of the fluid underpin consistent results over long shifts.

Other tools in the system

Steel shears, hydraulic demolition shears, Multi Cutters, and tank cutters generate varying loads. An oil supply with appropriate pressure limiting, adequate return capacity, and clean quick couplings prevents performance losses and heat spikes. For rock splitting cylinders, protect hose routing, maintain bend radii, and keep couplings clean – especially in dusty environments.

Oil supply across application areas

Concrete demolition and special demolition

High continuous loads and abrasive dust require robust filtration, seal-friendly oils, and cooling reserves. Short line runs and adequate hose cross-sections keep pressure losses low; this improves the efficiency of concrete demolition shears and steel shears. Additional shielding of hoses and disciplined coupling hygiene reduce ingression and extend service intervals.

Building gutting and cutting

Indoor environments impose requirements on emissions and noise. Electrically powered hydraulic power packs with sensitive valve technology and good temperature control ensure consistent oil quality and smooth operation with tank cutters and Multi Cutters. Low-odor fluids and enhanced ventilation support occupational hygiene in enclosed spaces.

Rock excavation and tunnel construction

Long hose runs and changing temperature conditions increase the importance of correct viscosity and line sizing. Low-loss couplings and effective cooling secure the performance of rock and concrete splitters in continuous operation. Where altitude or ambient shifts are expected, verify suction head and derate cooling accordingly.

Natural stone extraction

Temperature fluctuations outdoors require seasonally appropriate oil viscosity. Clean coupling and protection of couplings are central so that rock splitting cylinders work reliably and with repeatable accuracy. UV- and abrasion-resistant hose jackets can improve robustness on exposed routes.

Special applications

Special conditions – such as long distances between power pack and tool or elevated requirements for environmental compatibility – necessitate careful selection of oil, filtration, and line routing. Rapidly biodegradable oils can be suitable provided they match the seals and specifications of Darda GmbH. In addition, flow-optimized return concepts and thoughtful placement of monitoring points aid diagnostics over extended layouts.

Energy efficiency and resource conservation

Efficiency starts with design: appropriate flow rate instead of permanent throttling, short line runs, correct hose cross-sections, and demand-based cooling. Smooth-running hydraulics reduce heat losses, save fuel or electricity, and protect the oil. Regular care prevents premature oil changes and reduces downtime. Variable-displacement concepts, standby pressure reduction, and load-sensing control strategies help align power draw with the actual tool demand.

• Eliminate parasitic losses: Avoid undersized components and chronic bypassing.
• Thermal stewardship: Keep coolers clean; monitor oil temperature and viscosity.
• Condition-based service: Use oil and filter condition to optimize intervals and conserve resources.

Safety and environmental protection

Safe work requires depressurized coupling, intact hoses, and avoidance of leaks. Drips must be contained; absorbent materials should be ready. When working overhead or in confined spaces, line securing and mechanical protection are important. Requirements for handling hydraulic fluid may vary by location; proper storage and disposal protect people and the environment.

• Containment: Use drip trays and spill kits; label waste containers clearly.
• Inspection: Replace damaged hoses and couplings promptly; respect service life limits.
• Marking: Ensure clear identification of pressure ratings and flow direction on assemblies.

Documentation and best practices

The operating manual and maintenance instructions of Darda GmbH as well as recognized engineering rules form the framework for planning, operating, and maintaining the oil supply. Maintenance records, filter and oil change dates, and fault logs help operate systems reliably over time. Those who keep cleanliness, filtration, viscosity, and temperature in view achieve dependable results – especially with concrete demolition shears and rock and concrete splitters in demanding continuous service. Checklists for coupling hygiene, start-up, and shutdown complement operator training and support consistent quality across teams and shifts.