An overhaul program is a central building block for the safe, cost-effective, and sustainable use of hydraulic demolition and cutting technology. It describes the systematic, plannable refurbishment of tools and hydraulic power packs over their entire life cycle. Especially in application areas such as concrete demolition and special demolition, building gutting and concrete cutting, rock excavation and tunnel construction, natural stone extraction as well as in special demolition, the quality of the overhaul determines availability, performance, and occupational safety. Tools from Darda GmbH—such as concrete demolition shears and rock and concrete splitters, but also hydraulic power packs, combination shears, rock wedge splitters, Multi Cutters, steel shears, and tank cutters—benefit from clearly defined overhaul standards, because the loads in practice are high and tolerances are tight.
Definition: What is meant by overhaul program
An overhaul program is understood as the scheduled, documented restoration of the functionality of a tool or system to its intended condition. This includes diagnosis, disassembly, cleaning, measurement, replacement of wear parts, assembly, and final testing. The overhaul program is distinct from maintenance (care, lubrication, adjustment) and inspection (condition assessment) by specifically renewing worn, damaged, or aged components. The aim is stable performance, reduced probability of failure, and compliance with safety-relevant requirements. For hydraulic demolition tools this typically includes seals, guides, pins and bushings, cutting jaws or splitting wedges, valves, hydraulic hose lines, as well as the hydraulic accumulator, supplemented by a functional and pressure test at the end.
Objectives and benefits in concrete demolition and special demolition
A structured overhaul program stabilizes machine availability, reduces unplanned downtime, and contributes to operational safety. Especially concrete demolition shears need their nominal cutting force and precise jaw clearance to reliably cut reinforcement. Stone and concrete splitters only deliver their full splitting force when cylinders, sealing systems, and wedges are mechanically and hydraulically within specification. In noise-sensitive or vibration-critical areas—typical for special demolition or underground— a plannable overhaul cycle minimizes risks and simplifies deployment logistics. Economically, life-cycle costs decrease because core components are preserved and wear parts are renewed in a targeted manner. Ecologically, material is conserved and the service life of the base body is extended.
Relevance for concrete demolition shears and stone and concrete splitters
Concrete demolition shears are subjected to cyclic high loads: cutting jaws meet reinforced concrete, impacts and transverse forces act on pins and bearing points, fine dust penetrates guides. Without overhaul, jaw play increases, cutting edges become rounded, seals fatigue—the cutting performance drops and operability suffers. An overhaul restores geometry and hydraulic pressure, reduces leakage, and maintains jaw parallelism.
Stone and concrete splitters operate with very high pressures in the cylinder and localized peak forces on wedges. The overhaul safeguards the surface quality of the cylinder bore, the functionality of the seal packs, and correct wedge guidance. This keeps the splitting force reproducible, wedge insertion controlled, and reduces the risk of uncontrolled cracks in the rock. In natural stone extraction as well as in rock excavation and tunnel construction this is a key prerequisite for precise fracture patterns.
Typical components and wear patterns
Seals, guides, and hydraulic components
Seals age thermally and mechanically, which leads to micro-leaks and pressure loss. Guides develop play, piston rods no longer run true, valves respond sluggishly. An overhaul replaces seal packs, checks valve seats, and sets the hydraulics to target values. For hydraulic power packs this also includes filter condition, oil quality, and testing of the hydraulic accumulator.
Mechanical joints: pins, bushings, linkages
Transverse loads and contamination increase wear at joint points. Worn pins or ovality in bushings change the kinematics. As part of an overhaul program, fits are measured, pins replaced, and bushings brazed in or press-fitted to restore the original clearance.
Cutting and splitting tools
For concrete demolition shears, cutting edges lose sharpness or chipping occurs. Proper reconditioning includes regrinding within permissible limits or replacement. For stone and concrete splitters, wedges, spreading elements, and bearing surfaces are decisive; their geometry controls force flow and crack formation.
Hydraulic hose lines and connection components
Hose aging, abrasion, and kinks are frequent failure causes. An overhaul program defines replacement intervals and visual inspection points to enable preventive replacement. Connection fittings are checked for tightness and tightening torque.
Process of a professional overhaul
Diagnosis and assessment
At the beginning are visual inspection, functional check, and measurement of key parameters such as hydraulic pressure, leakage oil volume, and play in joints. Anomalies are documented.
Disassembly and cleaning
Disassembly is carried out in a controlled manner to protect components. Thorough cleaning enables the detection of fine scoring, cracks, or material fatigue. Particles in hydraulic channels are removed.
Measurement and evaluation
Critical dimensions (e.g., fits, runout, planarity/parallelism) are compared with reference values. The scope of the repair and the required spare parts are derived from this.
Repair and replacement
Wear parts such as seals, bushings, pins, cutting jaws, or wedges are replaced. Permissible rework on contact surfaces is performed as specified. Hydraulic components receive new seals; valves are checked and adjusted.
Assembly, testing, and documentation
Assembly follows defined torque and installation rules. This is followed by a final inspection with functional and pressure tests. All work steps and measured values are documented in a traceable manner.
Intervals and trigger criteria
Defined intervals are based on operating hours, load spectrum, and environmental conditions. In dusty environments or with high shock input—typical for concrete demolition and rock excavation—shorter cycles are advisable. Condition-based triggers include measurable pressure drop, increased leakage, excessive play, unusual noises, or temperature rise in the oil circuit. For concrete demolition shears, wear markers on cutting jaws serve as a practical limit; for stone and concrete splitters, seal condition and cylinder performance are decisive.
Documentation, quality assurance, and test certificates
A robust overhaul program relies on traceable documentation: check records, measured values, and releases provide the evidence. For hydraulic power packs, test reports with cavitation test, pressure test, and leakage test are suitable. For tools such as concrete demolition shears and stone and concrete splitters, functional tests under load are informative. The qualification of the personnel and suitable test equipment ensure the reproducibility of the results.
Safety and general compliance aspects
Overhauls serve occupational safety. Refurbished tools should reliably fulfill the intended functions. It is advisable to take relevant regulations and manufacturer specifications into account and to grant release only after a passed final inspection. Notes on CE marking, conformity, and documentation are to be understood in general terms and do not replace an individual assessment of the specific case.
Cost-effectiveness and sustainability
A well-designed overhaul program lowers life-cycle costs because plannable downtimes simplify deployment planning and prevent costly consequential damage. Preserving base bodies reduces material and energy demand, which is environmentally beneficial. For concrete demolition shears and stone and concrete splitters, replacing wear parts is usually far more resource-efficient than complete replacement.
Practical relevance by product group
Concrete demolition shears
Overhaul focuses on cutting jaws, pins/bushings, seals in the rotation or swing area, and the hydraulic circuit. The goal is to restore cutting performance, minimize play, and ensure tight, responsive hydraulics.
Stone and concrete splitters
The focus is on cylinders, seal packs, splitting wedges, and the guidance of spreading elements. Refurbishing wedge faces and setting correct hydraulic pressures are essential for reproducible splitting results.
Hydraulic power packs
Filters, oil quality, tightness, valves, the hydraulic accumulator, and temperature level are central points. A defined oil care regime and testing for cavitation protect connected tools over the long term.
Combination shears, Multi Cutters, and steel shears
Replaceable inserts, pins/bushings, and the planparallel alignment of cutting surfaces are checked and renewed. Pressure and flow parameters are set so that the cutting kinematics once again operate within the intended window.
Rock wedge splitters and tank cutters
For rock wedge splitters, tightness has top priority, supplemented by control of mechanical guidance. Tank cutters require particularly careful condition assessment and functional control, as cut quality and process safety are decisive.
Influence of application areas
Concrete demolition and special demolition
Changing material thicknesses, reinforcement densities, and installation situations generate changing peak loads. Overhaul programs therefore take dynamic load spectra and dust exposure into account.
Building gutting and concrete cutting
Sensitive tool guidance and high repeat accuracy are paramount. Overhauls precisely align the kinematics and reduce leakage to enable clean cuts.
Rock excavation and tunnel construction
High pressures, abrasive particles, and restricted access demand robust sealing systems and reliable hose routing. Overhaul intervals are often shorter here, and condition checks are more frequent.
Natural stone extraction
The desired fracture line in the rock requires defined splitting forces. Professional overhaul secures geometry and force flow and reduces scrap.
Special demolition
Special boundary conditions require adapted testing and release processes. Detailed documentation helps demonstrate suitability for the respective purpose.
Integration into daily operations
A practical overhaul program is embedded in deployment planning. Tools are submitted at regular intervals based on operating hours or at the end of a project. Service kits for critical components are kept in stock so overhauls can be completed quickly. Condition data from functional tests flow into the next interval planning—creating a learning system of predictive maintenance.
Differentiation: maintenance, overhaul, modernization
Maintenance preserves condition through cleaning, lubrication, adjustment, and replacement of operating supplies. The overhaul restores the intended condition when relevant deviations are present. Modernization or retrofit can be useful if technical solutions have proven themselves, for example through updated valve technology or optimized sealing materials—the decision should always be application-specific and carefully weighed.
Quality characteristics of a good overhaul program
Quality is recognizable by clear test steps, measurable acceptance criteria, and complete documentation. For concrete demolition shears these include defined limits for play and jaw geometry; for stone and concrete splitters tightness and the achievable splitting force at a defined pressure. Transparency about the scope of parts, clean surfaces, and a traceable test run under load round off the process.