Impact loads are ubiquitous in demolition, deconstruction and rock cutting/processing. They arise wherever forces are not introduced slowly but abruptly. For users of concrete demolition shear, stone and concrete splitter devices, combination shears, multi cutters, steel shear, tank cutters and the associated hydraulic power pack, the topic is central: Impact loads affect tool service life, the integrity of structures as well as occupational safety at the worksite — whether in concrete demolition and special deconstruction, in building gutting and cutting, in rock demolition and tunnel construction, in natural stone extraction or in special operations.
Definition: What is meant by impact load
Impact load (also impact loading or sudden load) refers to a short-term, very rapid increase in force or pressure with high amplitude and short duration. It differs from static or slowly varying loads through its dynamics: inertia, vibrations and pressure surges are activated. In practice, this appears as a strong “jerk,” a pressure surge in the hydraulics, an impact of tool jaws on the workpiece, or the abrupt tearing open of a concrete or rock structure. Impact loads lead to transient vibrations, raise peak forces and can cause micro-damage, crack formation and premature wear.
Physical fundamentals of impact load
Impact loads are based on momentum and energy exchange. The shorter the contact time and the harder (stiffer) the interacting partners, the greater the peak forces. Impulse results from force times duration; if the duration shortens, peak forces rise. Materials respond differently: concrete and natural stone appear stronger under rapid loading but fracture more brittlely; steel shows toughness, yet can fail at notches and high strain rates. In hydraulic systems, pressure surges (water hammer) occur when flow is abruptly braked or diverted, for example when a valve closes quickly or when the shear makes sudden contact with the component. Pressure waves travel through lines, reflect at bends and can superimpose. Resonances and natural frequencies of the machine, excavator attachment and structural element determine how strongly impact loads are amplified or damped.
Causes and triggers in practice
Impact loads rarely occur randomly; they typically arise from certain work situations, tool positions or material properties. Common triggers include the abrupt closing of jaws, sudden “punch-through” on the last residual material, blocked movements followed by release, hard strikes, rebound effects, and hydraulic pressure surges during load changes.
Concrete demolition and special deconstruction
When biting off edges of components, separating reinforced zones or breaking out individual segments, impact loads occur if the concrete demolition shear suddenly breaks through or the reinforcement gives way abruptly. Jaws jamming on the component and the subsequent release also lead to transient peak loads.
Building gutting and cutting
When cutting thin-walled sheet with steel shear or tank cutters, impulsive loads occur if the workpiece springs and rebounds. In combined cutting and gripping operations, switching moments of the hydraulics generate short-term pressure spikes.
Rock breakout and tunnel construction
When splitting rock with a hydraulic wedge splitter, the crack can run suddenly. Stored elastic energy is released in the process. Irregular joints and anisotropic layering promote unpredictable load peaks.
Natural stone extraction
During controlled block release, impact loads occur when wedges or splitting cylinders exceed the critical point of fracture formation and the block tears off or loosens abruptly.
Special operations
In rescue and deconstruction work under time pressure, rapid tool actuations, short contact times and elevated pressure surges in the hydraulics occur more frequently.
Effects on components, materials and hydraulics
Impact loads affect structure, tool and system. They accelerate wear, increase the risk of crack formation and reduce precision. In hydraulics they promote seal wear, hose damage and valve seat fatigue.
- Components: micro-crack growth in concrete, spalling, sudden failure of brittle zones, unexpected release of component segments.
- Tools: cutting and tooth edges can chip, jaws and pins are shock-loaded, bearing points experience notch impacts.
- Hydraulic power units: pressure peaks load pumps, accumulator, valves and hoses; cavitation can occur when the load drops abruptly.
Impact load with concrete demolition shear and stone and concrete splitter devices
Concrete demolition shear and stone and concrete splitter devices are particularly relevant because they often trigger the moment of crack propagation and thus generate the greatest dynamics. The right approach determines peak loads and the quality of the break.
Concrete demolition shear: typical situations and reducing impact loading
- Segmented approach: first bite component edges, then remove layer by layer. This reduces sudden “punch-through.”
- Consider reinforcement: weaken the concrete core first, then separate reinforcement in a controlled manner. Avoid pure tensile loading on single bars.
- Use jaw geometry: begin with the rear, more powerful zone and work toward the tip; more uniform contact time reduces peak forces.
- Stable support of the component: free-hanging parts tend to kick back and oscillate; proper bearing and shoring reduce impact load.
Stone and concrete splitter devices: controlled splitting
- Borehole layout: choose hole diameter, depth and spacing so the crack runs in a controlled way and does not suddenly break through the entire cross-section.
- Stepwise pressure increase: raise pressure in stages; watch acoustic and visual signs of crack propagation.
- Allow elastic relaxation: pause briefly after the first crack advance; the system settles and pressure peaks drop.
- Check contact surfaces: clean, correctly aligned splitting wedges and cylinders minimize notch and crushing peaks.
Calculation, measurement and assessment
The assessment of impact loads is based on measured data and traceable estimates. In practice, a few measurement points often suffice to identify hotspots.
- Pressure and force measurement: fast-response pressure sensors close to the tool, occasionally strain gauges at critical points.
- Event recording: data loggers capture peak values and event duration; dynamic amplification factors can be derived.
- Vibration analysis: accelerometers reveal natural frequencies and damping; resonances can be specifically avoided.
- Assessment: rather than peak values only, also consider energy density (force over time) and repetition rate to judge fatigue.
Technical measures to limit impact loads
Technology and method interlock. A good combination reduces pressure surge, kickback and vibrations alike.
- Hydraulic damping: use of accumulator, throttles and fast pressure relief hydraulic valve; gentle ramps for start/stop.
- Line routing: short, generously sized hoses with minimal deflection; quick coupling with high flow reduces pressure jumps.
- Valve strategy: avoid abrupt switching; pilot and proportional technology for smooth movements.
- Mechanical buffers: end stops and damping elements at travel ends where appropriate.
- Tool geometry: progressive engagement of cutters/jaws distributes contact time and reduces peak forces.
- Stable support: secure bearings and shoring prevent uncontrolled movements and rebound.
Work methodology and operation
Operation has the strongest influence on impact load levels in day-to-day work. Anticipatory working and clean sequences make the difference.
- Meter the feed: increase force application evenly; no “full throttle on contact” maneuvers.
- Pre-breaking and pre-cutting: weaken material first, then separate; avoids abrupt breakthroughs.
- Control load paths: anticipate tensile and bending reactions of the component; avoid unnecessary energy storage in the structure.
- Team communication: coordinate demolition direction, release timing and hazard zone; no one in the swing or drop area.
- Tool positioning: set jaws parallel and with full surface; edge attacks only in a controlled, staged manner.
Material and environmental factors
Materials respond very differently to impact loads depending on their condition. This applies to concrete, masonry, steel and natural stone as well as to composite structures.
- Concrete: strength class, age, moisture, concrete structure (matrix) and reinforcement influence fracture behavior and dynamics.
- Rock/natural stone: layering, joints, water content and temperature control crack propagation and energy release.
- Steel parts: notches, corrosion and cold working increase notch sensitivity and the risk of impact failure.
- Environment: low temperatures make materials more brittle; moisture can increase damping or promote cavitation.
Impact load and safety
Safety aspects come first. Impact loads can release or throw parts unexpectedly, pressure surges can stress lines and couplings. Protective measures must always be taken and adapted to the situation.
- Secure the hazard zone: keep swing and drop zones clear; maintain visual and voice contact within the team.
- Personal protective equipment: eye, hand and foot protection as well as suitable protective clothing.
- Hydraulic safety: regularly check hoses, quick coupling and seals; switch to zero pressure before maintenance.
- Retaining systems: choose hose restraints and line routing so that failure does not lead to whipping.
Maintenance and condition monitoring
Impact loads leave traces. Careful maintenance preserves function and reduces consequential damage.
- Tool inspection: check jaws, cutters, pins and bearings for chipping, play and scoring.
- Hydraulic care: regularly check oil condition (hydraulic oil analysis), filters and accumulator; investigate unusual noises and temperature peaks.
- Documentation: record conspicuous events; recurring peaks indicate optimization potential in method or technology.
Interfaces to other products and applications
Impact loads affect the entire system of attachment and hydraulic power units. Combination shears, multi cutters, steel shear and tank cutters react similarly sensitively to abrupt load changes. In concrete demolition and special deconstruction, tuned hydraulic parameters and calm valve control help. In building gutting and when cutting thin-walled materials, progressive cuts are advantageous. In rock breakout, tunnel construction and natural stone extraction, drilling and splitting strategy determine dynamics and safety. Special operations require particularly clear procedures to keep abrupt events manageable.
Planning and optimization for lower impact loads
Impact loads can be minimized already in preparation. Good planning reduces risks and increases efficiency.
- Pre-analysis: determine material, reinforcement layout, supports and load paths; define the demolition sequence.
- Tool selection: choose the appropriate concrete demolition shear, stone splitter or concrete splitter and shears to suit cross-section and material behavior.
- Parameterization: match working pressure and flow to the task; use gentle start and stop ramps.
- Staging: divide large cross-sections into manageable segments; controlled fracture guidance instead of full break in one go.
Legal and organizational notes
Requirements from occupational safety and technical rules generally demand a hazard analysis, suitable selection of work equipment and qualified personnel. Specific measures must always be planned on an object-specific basis and checked regularly. The operating manual and maintenance instructions of the equipment used must be observed and form the basis for safe operation.