A hydraulic demolition shear is a central tool in selective concrete demolition, special demolition, as well as in gutting works and cutting of reinforced concrete components. It operates with low vibration, precisely and in a controlled manner, enabling both load-bearing and non-load-bearing elements made of reinforced concrete, masonry, or natural stone to be dismantled in a material-appropriate way. In combination with concrete pulverizers, stone and concrete splitters, steel shears, Multi Cutters, tank cutters, and matching hydraulic power units from Darda, a continuous, application-specific system is created for deconstruction under construction site conditions with confined spaces and high requirements for emission and noise reduction.
Definition: What is a hydraulic demolition shear
A hydraulic demolition shear is a hydraulically driven jaw tool for gripping, crushing, pulverizing and/or cutting mineral construction materials such as concrete, reinforced concrete, and masonry. Force transmission takes place via one or more hydraulic cylinders to a pair of jaws with cutting edges, tooth bars, or pulverizing profiles. Hydraulic demolition shears are used as hand-held tools with a hydraulic power pack or as an attachment on carrier machines. In deconstruction they are often combined with concrete pulverizers (focus on concrete crushing), combination shears (interchangeable jaw geometries), steel shears (for reinforcing and structural steel), and Multi Cutters (broad material spectrum) to separate concrete and reinforcement by type.
Design features and jaw types
Hydraulic demolition shears typically consist of a main body with a pivot-mounted moving and fixed jaw, high-strength pin bearings, replaceable cutting blades or tooth bars, and one or more cylinders to generate closing force; jaw geometry ranges from pulverizing shapes for breaking concrete to cutting contours for reinforcement, up to combined profiles in combination shears, while rotators (360°) facilitate positioning, pressure relief and changeover valves ensure hydraulic flow, and oil supply is provided by hydraulic power packs or carrier machines; key parameters include opening width, cutting and crushing force, cycle time, self-weight, permissible hydraulic pressure and flow rate, with matching to member thickness, reinforcement content, and accessibility being decisive.
Structure and operating principle
At its core, the hydraulic cylinder converts applied oil pressure into linear force. This is transferred to the jaws via the kinematics (links, pins, bearings). Depending on the geometry, the jaws pulverize the concrete or they cut reinforcement and plates. A hard, wear-resistant cutting edge separates metallic inserts, while toothed areas break open the concrete. For hand-held tools, a hydraulic power pack provides the required pressure and flow. As an attachment, the carrier machine supplies the hydraulics. A rotator allows precise alignment to the component edge, increasing process reliability and reducing side loads.
Hydraulic power packs and pressure supply
Hydraulic power packs from Darda GmbH deliver the defined pressure and flow rate for hand-held hydraulic demolition shears and complementary tools. Important parameters are cold-start behavior, stable pressure regulation, sufficient cooling, and filtration to ensure oil cleanliness. Quick couplings simplify tool changes. A correctly sized supply prevents power losses, excessive heating, and premature wear.
Application fields in concrete demolition and special demolition
Hydraulic demolition shears demonstrate their strengths wherever precise, low-vibration work is required and cut or fracture lines must be produced in a controlled way. Typical application areas at Darda GmbH are:
- Concrete demolition and special demolition: controlled removal along component edges, creation of openings, deconstruction of walls, slabs, and beams, targeted breakout in foundation areas.
- Gutting works and cutting: selective deconstruction in existing buildings, exposing reinforcement, followed by cutting the rebar with steel shears or Multi Cutters.
- Rock excavation and tunnel construction: removal of shotcrete or breakouts at crown and sidewalls; for massive rock volumes, hydraulic rock and concrete splitters are suitable additions to further minimize vibrations.
- Natural stone extraction: trimming and sizing of edges on blocks; for primary extraction steps, stone and concrete splitters are often the more economical solution.
- Special operations: work in confined spaces, in sensitive areas with noise and vibration limits, or for low-spark cutting; for thin-walled tanks and apparatus, specialized tank cutters are available.
Selection, sizing, and performance parameters
The correct selection is based on material, member thickness, reinforcement content, and accessibility. Opening width and jaw shape must match the component geometry, cutting force the maximum reinforcement, and crushing force the concrete strength class. Self-weight determines handling (hand-held) or the attachment class (carrier machine). Shorter cycle times accelerate the process but require adequate hydraulic supply. In combination with concrete pulverizers or combination shears, the sequence of concrete reduction and reinforcement separation can be planned efficiently.
- Material and strength: reinforced concrete with a high strength class requires high crushing forces and robust tooth profiles.
- Reinforcement: for thick or high-strength steels, supplement with steel shears or Multi Cutters.
- Component geometry: opening width, jaw length, and rotator configuration determine access to edges and corners.
- Environmental requirements: vibration and noise limitations favor hydraulic demolition shears or stone and concrete splitters.
Work method: from approach to separation
Efficient deconstruction with the hydraulic demolition shear follows a structured approach. First, the component is analyzed: reinforcement layout, stress state, connection details. Next comes a safe bite at edges or prepared openings, followed by controlled breaking into manageable pieces. Exposed reinforcement is cut with steel shears or Multi Cutters. Source-separated placement and transport of the fractions facilitates recycling logistics.
- Analyze the component and define the cut path.
- Position with minimal side loads, use the rotator.
- Pre-break the concrete with a pulverizing jaw geometry.
- Cut the reinforcement with an appropriate cutting tool.
- Source-separated placement for recycling and disposal.
Dust and noise reduction
Hydraulic shears are inherently low-vibration and comparatively quiet. Additional dust reduction is achieved through targeted wetting at the work area, short working paths, and continuous removal of crushed material. A well-matched tool selection lowers the energy required per cut and reduces secondary noise.
Maintenance, wear, and service life
Regular inspections increase availability: regrind or replace cutting blades, check tooth bars, keep pins and bearings free of play, inspect seals and hose bundles, and keep hydraulic oil clean and within specification. Proper pressure setting prevents overload and reduces wear on jaws and kinematics. Operating-hour- and condition-based maintenance supports predictable servicing.
Safety and legal notes
Working with hydraulic demolition shears requires appropriate instruction, personal protective equipment, and a risk assessment. The work area must be cordoned off, and loose components secured against unintentional falling. Hydraulic systems must be depressurized before maintenance work. When working on tanks or in areas with potentially hazardous media, additional protective measures and clearances must be planned. Applicable local regulations, standards, and recognized rules of technology must always be observed; binding case-by-case assessments remain the responsibility of the competent professionals.
Demolition shear, concrete pulverizer or stone and concrete splitter?
The hydraulic demolition shear is universal for reducing concrete components and exposing reinforcement. Concrete pulverizers are optimized for efficient pulverizing of concrete and deliver high liberation performance with low vibration. Stone and concrete splitters as well as rock splitting cylinders act via controlled splitting forces and are particularly advantageous for massive cross-sections, sensitive buildings, or in rock. In day-to-day deconstruction, the combination leads to the goal: first split or pre-break in a targeted manner, then shape with the demolition or concrete shear and separate the reinforcement with steel shears or Multi Cutters.
Integration into deconstruction and refurbishment concepts
For an efficient workflow, tools, hydraulic power packs, logistics, and disposal are coordinated during planning. Selective dismantling, short material paths, and source-separated sorting increase the recycling rate and reduce costs. The ability to work with a hydraulic demolition shear in a low-emission and precise manner supports deconstruction concepts in existing buildings, inner-city locations, and sensitive environments.
Typical mistakes and how to avoid them
- Unsuitable jaw geometry for the material and task.
- Opening width too small for the member thickness.
- Side loads due to incorrect approach; use the rotator consistently.
- Insufficient flow rate or incorrect pressure at the hydraulic power pack.
- Missing separation of concrete and reinforcement using appropriate complementary tools.
Technical developments and trends
Modular systems with changeable jaws (combination shears), improved wear-resistant steels, optimized hydraulics for shorter cycle times, data-based condition monitoring, and ergonomic handling shape current development. There is growing demand for dust- and noise-reduced methods as well as solutions for confined workspaces. In combination with the tools and hydraulic power packs from Darda GmbH, these requirements can be systematically implemented across different application areas.