Lubrication

Lubrication is a central topic for the reliability and service life of hydraulically powered tools in concrete demolition, rock cutting/processing, and natural stone extraction. It reduces friction, protects against wear and corrosion, and influences energy efficiency. Especially for equipment such as concrete demolition shears, stone and concrete hydraulic splitters, hydraulic demolition shears, or hydraulic power units, the right lubrication strategy determines whether systems operate stably, safely, and with consistent performance. This article combines fundamental knowledge and practical guidance and relates it to the products and application areas of Darda GmbH—objective, precise, and without promotional language.

Definition: What is meant by lubrication

Lubrication refers to the targeted supply of surfaces with a lubricant to reduce friction and wear, dissipate heat, and protect components against corrosion. In tribology, a distinction is made between boundary, mixed, and hydrodynamic lubrication. Depending on the type of motion (sliding, rolling, oscillating), load, temperature, and environmental conditions, greases, oils, or special pastes are used. In hydraulic systems, hydraulic fluid performs not only power transmission but also a lubrication function: it forms a load-bearing film in pumps, valves, cylinders, and at sealing surfaces.

Fundamentals and practice of lubrication in demolition and rock cutting/processing

High forces, impact loads, dust, moisture, and sometimes wide temperature ranges act in demolition and splitting processes. A robust lubrication strategy combines the right material selection with suitable intervals and consistent cleanliness at lubrication points. For concrete demolition shears, slewing bearings, pin–bushing pairs, and cylinder mounts are critical points; for stone and concrete hydraulic splitters, the wedge and counter-wedge surfaces, guides, and hydraulic connections are key. The lubricant must adhere where it is needed and at the same time bind contamination and purge it from the bearing zone, without damaging seals.

Types of friction and lubricant films

In slowly oscillating bearings, boundary or mixed friction often predominates. Here, EP additives and, where appropriate, solid lubricants (e.g., MoS2 or graphite) are advantageous. In fast-flowing hydraulic clearances (pumps, valves), hydrodynamic lubrication predominates; viscosity and cleanliness of the hydraulic fluid are then crucial.

Typical loads on concrete demolition shears

Concrete demolition shears operate under extreme dust exposure and experience fluctuating load peaks. Greases must offer good adhesion, water resistance, and pressure resistance (EP). Regular greasing flushes abrasive particles out of the bushings and keeps the pivots load-bearing.

Typical loads on stone and concrete splitters

The wedge mechanism requires a thin, uniform lubrication or assembly film on the sliding surfaces to prevent galling damage and to control friction in a targeted manner. Excessive greasing can, however, contaminate boreholes and bind chips. The rule here is: apply cleanly, remove excess, and keep sealing points and couplings free of dirt.

Hydraulic fluids: selection, viscosity, and additives

Hydraulic power packs, as used in combination with concrete demolition shears, stone splitting cylinders, hydraulic demolition shears, steel shears, multi cutters, or tank cutters, require a fluid with stable viscosity and high resistance to aging and corrosion.

• Viscosity grades: ISO VG 32/46/68 are used depending on practice. Colder operations (e.g., in winter or in tunnel operations) favor lower viscosities, higher ambient temperatures favor higher ones.
• Fluid types: HLP fluids provide proven wear protection; HVLP fluids deliver an increased viscosity index for wide temperature windows.
• Additives: Anti-wear, corrosion inhibitors, antioxidants, and defoamers safeguard function. Compatibility with seals must be considered.
• Cleanliness: Particles and water are the main causes of premature component wear. Filtration concepts and regular oil changes are essential.

Practical reference

With frequent switching between outdoor construction sites and interior demolition, a fluid with a high viscosity index is recommended to cover both cold starts and continuous operation in warm environments. The fluid is also the lubricant for pump bearings, spools, and cylinders—a clean hydraulic system means less friction and longer service lives for tools from Darda GmbH.

Greases for shock- and dust-loaded applications

For pivots, pins, and bushings on concrete demolition shears, hydraulic demolition shears, multi cutters, and steel shears, adhesive EP greases of NLGI grade 1–2 have proven effective.

• Load-carrying capability: EP additives and, where appropriate, solid lubricants increase emergency running properties.
• Adhesion: Tacky base oils and adhesion improvers reduce washout by water or mud.
• Temperature range: Operation in tunnels or in winter cold requires low-temperature pumpability; summer operation requires oxidation stability.
• Water resistance: Important for wet boreholes in natural stone extraction or during rock excavation.

Amount and frequency of application

“As much as necessary, as little as possible”: enough grease to remove abrasion and dust without over-pressing seals. Visible discharge at bearing edges is often a good sign of sufficient flushing—however, excessive grease collars collect dust and should be removed.

Maintenance intervals and a structured sequence

The intervals depend on utilization, dust and water exposure, and the specific components. A structured sequence increases process reliability.

1. Daily before starting work: Visual inspection of lubrication points, re-grease the main pivots on concrete demolition shears and hydraulic demolition shears, apply a thin film to wedge faces of stone and concrete hydraulic splitters.
2. During operation: With intense dust events, intermediate greasing of heavily loaded pivots; for splitters, keep wedge faces clean.
3. After operation: Clean lubrication points, remove grease and dust collars, apply a corrosion protection film to exposed steel surfaces.
4. Weekly/project end: Check hydraulic connections, quick couplings, and sealing surfaces; visually check fluid level and color on the hydraulic power pack.

Influence of environment and application area

Lubrication is environment-dependent engineering: the application area shapes the material selection and the interval.

• Concrete demolition and special demolition: Cement dust is highly abrasive. Shorter greasing intervals on concrete demolition shears and steel shears protect pins/bushings; an adhesive grease removes particles.
• Building gutting and cutting: Lower dust volumes but frequent load changes. A universal EP grease and clean couplings on the hydraulic power pack stabilize operation.
• Rock demolition and tunnel construction: Moisture, mud, and temperature fluctuations. Water-resistant, high-adhesion greases and hydraulic fluids with a high VI are advantageous.
• Natural stone extraction: Wet drilling and fine rock abrasion; thinly applied, clean lubricant films on splitting wedges and regular re-greasing of guides.
• Special applications: Unusual temperatures or media require matched lubricants. As a general rule, select carefully with an eye on seal compatibility and safety.

Typical lubrication points on equipment

An equipment-specific view helps ensure no points are overlooked.

• Concrete demolition shears: Main jaw pivot, secondary pivots of cutting/crushing segments, cylinder eyes, slewing bearing of the rotator (if present). Cutting edges themselves are not greased; apply corrosion protection only to bare, non-working surfaces.
• Stone and concrete hydraulic splitters: Apply a thin film to wedge and counter-wedge faces, wedge-group guides; protect contact surfaces in the borehole from contamination. Keep hydraulic connections clean; do not grease coupling seals if this could impair the sealing materials.
• Stone splitting cylinders: Protect piston rods from corrosion, lubricate the bearing points of the mounts, keep abutment faces clean.
• Hydraulic demolition shears, multi cutters, steel shears: Regularly re-grease all pin–bushing pairs; for slewing bearings, pay increased attention to the flushing action of the grease.
• Tank cutters: Supply rotation and guide points with a suitable grease, keep lubricant away from cutting areas.
• Hydraulic power packs: Ensure hydraulic fluid quality; bearings and drives are usually lifetime-lubricated, yet fluid condition is still decisive for overall lubrication of connected tools.

Common mistakes and their consequences

Incorrect selection or application of lubricants quickly leads to increased wear.

• Too infrequent re-greasing: galling, pitting, increased noise, heating at pivots.
• Over-greasing: seal extrusion, unnecessary friction, dust binding.
• Incorrect viscosity of the hydraulic fluid: cavitation damage with fluid that is too thin, performance losses and heat generation with fluid that is too viscous.
• Incompatible additives: swelling of seals, leaks, altered friction coefficients.
• Mixing of greases: structural breakdown, oil separation, loss of EP performance.

Condition monitoring, documentation, and oil analyses

Systematic control extends service life and makes lubrication plannable.

• Lubrication plan: Document fixed intervals, defined lubrication points, and quantities.
• Oil analyses: Particle count, water content, viscosity trend, and additive condition provide early indicators.
• Temperature and noise observation: Increases often indicate inadequate lubrication.
• Grease assessment: Color, consistency, and particle inclusions provide indications of overload or contamination.

Occupational safety and environmental aspects

When handling lubricants, skin protection, cleanliness, and leak avoidance are important. Lubricants do not belong in the environment; their storage and disposal should comply with applicable requirements. Information in operating manuals from Darda GmbH and general safety rules must be observed. Legal requirements may vary by region; these notes are of a general nature.

Quality in assembly and repair

Clean assembly surfaces, correct torques, and targeted use of assembly pastes ensure reproducible bolt preload and prevent fretting corrosion. After repairs to hydraulic components, careful flushing and bleeding are advisable so that the lubricant film is established immediately.

Energy efficiency through appropriate lubrication

Lower friction reduces the power draw of hydraulic power packs and decreases heating. On concrete demolition shears, well-supplied bearings lead to smoother movement, shorter cycle times, and fewer load peaks on cylinders and lines.

Checklist: lubrication in the daily routine

1. Before operation: Visual inspection, grease main bearings, thin film on wedge faces, check hydraulic fluid level.
2. During operation: For dust peaks, intermediate greasing, keep couplings clean.
3. After operation: Cleaning, remove excess grease, apply corrosion protection, document observations.