Lubricating grease is a key item of operating supplies in heavy demolition and extraction technology. Wherever bolts, bushings, spherical plain bearings, and sliding surfaces operate under high loads, impact loads, dust, and moisture, a suitable grease ensures low-friction operation, wear protection, and corrosion resistance. In Darda GmbH applications—from concrete demolition through rock excavation and tunnel construction to natural stone extraction—this particularly concerns the joints of concrete demolition shears and the bearing points of rock and concrete splitters as well as other hydraulically driven tools and power units.
Definition: What is meant by lubricating grease
Lubricating grease is a semi-solid lubricant composed of a base oil, a thickener (soap or complex structure), and additives. It combines the lubricating effect of an oil with the adhesion and sealing effect of a solid. Typical tasks include reducing friction, protecting against wear, corrosion and water, damping vibrations, and sealing against dust. Unlike hydraulic oil, grease remains at the lubrication point and is not circulated; it is therefore suitable for pins, bushings, plain bearings, rolling bearings, slideways, and coupling connections—but not as a working medium in hydraulic systems.
Structure and operating principle of lubricating greases
Greases consist of a base oil (mineral or synthetic) that is bound into a sponge-like matrix by the thickener. This matrix stores the oil and releases it in a targeted manner to the contact zone under load, motion, and temperature. Additives such as EP (Extreme Pressure) packages, anti-wear agents, corrosion inhibitors, and antioxidants stabilize the lubricating film. Optionally used solid lubricants (e.g., molybdenum disulfide, graphite) support performance in boundary lubrication and under shock loading. The NLGI grade describes the consistency (e.g., 0, 1, 2), worked penetration the deformation resistance, and the drop point the thermal stability. For tools with alternating load peaks—for example, the kinematics of concrete demolition shears—a mechanically stable EP multipurpose grease with high worked stability, good adhesion, and pronounced water and corrosion protection is often the right choice.
Lubricating grease in concrete demolition, rock excavation, and tunnel construction
In Darda GmbH’s application areas, high contact pressures, vibrations, dust, moisture, and sometimes aggressive media coincide. Suitable greases must therefore meet several requirements simultaneously.
Typical lubrication points on tools and power units
- Concrete demolition shears: pins/bushings of the scissor arms, joints of the kinematics, bearing points of the cylinder mount, supports and guiding points
- Rock and concrete splitters as well as rock splitting cylinders: guide and bearing points of the cylinder heads, pin connections at mounts, where applicable sliding surfaces of wedge and guide elements
- Combination shears, multi cutters, steel shears, tank cutters: joint pins, plain bearings, rolling bearings, and guide rails
- Hydraulic power pack: bearings of drives/auxiliary systems (e.g., fan bearings, coupling points), where grease-lubricated
Environmental influence
- Concrete demolition and special deconstruction: high shock loads, abrasive dust—need for EP greases with strong adhesion and abrasion protection
- Rock excavation and tunnel construction: moisture/water, possible temperature fluctuations—water-resistant, corrosion-inhibiting greases with good pumpability
- Natural stone extraction: continuous dust generation, changing weather—mechanically stable, tacky multipurpose greases
- Building gutting and cutting: frequently changing load spectra, precise tool motion—clean, even lubrication to safeguard the kinematics
- Special applications: specific media/temperatures—careful selection regarding material compatibility and environmental requirements
Selecting the appropriate grease: criteria and key values
The right grease selection depends on the design of the lubrication point, load profile, temperature, environmental media, and application method (manual or centralized lubrication).
Temperature range and base oil
- Typical operating windows: approx. −30 to +140 °C; high-performance greases beyond this
- Base oil viscosity: higher viscosity for high contact pressures and slower movements; lower viscosity for cold and better pumpability
- Synthetic oils (e.g., PAO) for an extended temperature range and oxidation stability
Thickener chemistry
- Lithium/lithium complex: universal, good temperature behavior
- Calcium sulfonate complex: excellent water and corrosion protection, high mechanical stability, suitable for wet/tunnel conditions
- Aluminum complex, etc.: good adhesion, increased temperature resistance—depending on the use case
NLGI grade and pumpability
- NLGI 2 for most joints on concrete demolition shears and other shears (good structural stability)
- NLGI 1 or 0 for cold environments or long lines in centralized lubrication
- Observe the pump limits of the lubrication equipment used
EP additives and solid lubricants
- EP/AW packages to prevent scuffing under shock load
- Solid lubricants (e.g., MoS2) for boundary lubrication and low speed
Water and corrosion protection
- Low washout tendency, high water resistance
- Effective inhibitors for steel surfaces in humid, dusty environments
Material compatibility
- Check compatibility with seals and coatings (e.g., NBR, HNBR, FKM, PU)
- When changing the grease type, observe chemical compatibility
Application: relubrication, quantities, and procedure
The best grease quality only works with correct application. Relubrication intervals depend on usage intensity, environment, and bearing design.
Recommended relubrication procedure
- Clean the lubrication point (remove dust/particles), clean the grease nipple
- Slowly pump in the appropriate grease via grease gun or cartridge
- Relubricate until fresh grease becomes visible at the outlets
- Wipe off excess on the outside to reduce dirt adhesion
- Document lubrication points (interval, quantity, grease type) for maintenance planning
Centralized lubrication
- Suitable for equipment with many lubrication points, ensures even supply
- Match NLGI grade and base oil viscosity to line cross-section and pump type
- Regularly check distributors (progressive/multi-line principle) for proper function
Lubrication schedules for concrete demolition shears and rock and concrete splitters
For the joints of concrete demolition shears, short relubrication intervals under high loads are common, as shock loads stress the lubricating film. For rock and concrete splitters, reliable lubrication of the pin and guide bearings is paramount to ensure friction-locked power transmission and repeatable motion. The specific interval design follows the actual load spectrum, the daily changing operating environment, and the sealing configuration of the bearing points.
Practical tips
- After heavy water exposure (rain, tunnel water), relubricate early
- In cold conditions: consider a softer consistency (NLGI 1/0) or a synthetic base oil
- With heavy dust exposure: use tacky, mechanically stable EP greases
Grease change, miscibility, and condition monitoring
Thickener systems are not always compatible with each other. When switching to a different chemistry (e.g., from lithium complex to calcium sulfonate complex), it is advisable to expel as much old grease as possible and clean the lubrication point. Observable signs of problems include oil separation, softening, or hardening. A simple condition check is performed visually at the outlets as well as by monitoring noise and temperature in operation.
Quality and test values: practical guidance
Relevant key values support selection:
- Worked penetration (consistency, DIN/ISO)
- Drop point (thermal load capacity)
- Four-ball weld load/carrying capacity (EP performance)
- Water washout test (resistance to washout)
- EMCOR corrosion (corrosion protection under moisture)
- Oxidation stability (long-term behavior)
Environmental and occupational safety
Handle greases properly: avoid skin contact where possible, dispose of soiled cloths and spent greases correctly, and prevent carry-over into soil and water bodies. In sensitive zones (e.g., tunnels with water ingress), rapidly biodegradable formulations can be sensible, provided they meet the technical requirements. Legal requirements and local regulations must be observed in general.
Avoiding typical mistakes
- Unsuitable NLGI grade: poor pumpability or insufficient structural stability
- Overly long relubrication intervals: increased wear, onset of corrosion
- Over-greasing: seal stress, temperature rise, excessive grease consumption
- Incorrectly mixed greases: loss of consistency, oil separation
- Contaminated lubrication points: particle abrasion, running noise
Guide to grease selection for demolition and extraction tools
- Load profile: high shock loads require robust EP performance
- Environment: water/dust → water-resistant, tacky greases with corrosion protection
- Temperature: operating window and drop point suitable for practice
- Application: centralized lubrication requires pumpable consistency/base oil
- Material compatibility: consider seals and coatings
- Maintenance: relubrication capability, visual checks, documentation
Lubricating grease in the context of other tools
In addition to concrete demolition shears and rock and concrete splitters, combination shears, multi cutters, steel shears, and tank cutters also benefit from load-appropriate lubrication of the pin and bushing bearings. A stable grease supply increases the operational safety of the kinematics, reduces friction losses, and supports smooth running—especially with frequent load changes and alternating cutting/splitting operations.