Hydraulic rotation describes the targeted, continuous rotational movement of an attachment or handheld tool by means of hydraulic pressure. In practice, it is a core functional feature of demolition and cutting tools, enabling grapples, shears, or splitting wedges to be aligned precisely and workflows to be executed safely, accurately, and time-efficiently. In the context of Darda GmbH, this particularly involves applications with concrete demolition shears, combination shears, steel shears, multi cutters, tank cutters, as well as the fields of concrete demolition and deconstruction, special demolition, strip-out, rock breakout, tunnel construction, natural stone extraction, and special operations. Wherever stone and concrete splitters or stone splitting cylinders are used, hydraulic rotation supports correct positioning, edge alignment, and controlled force application.
Definition: What is meant by hydraulic rotation
By hydraulic rotation we mean the rotational movement of a tool head or assembly generated by a hydraulic motor, usually with endless 360° capability. A rotator or rotary drive converts flow from the hydraulic system into torque and rotational speed. A rotary union routes the medium pressure-tight so that the tool is reliably supplied even while rotating. Key parameters include torque, rotational speed, permissible radial and axial loads, the type of control (on/off or proportional), as well as behavior under pressure spikes and load changes.
Technical design and mode of operation
A rotation system for demolition and cutting tools combines a hydraulic motor, gearbox, bearing arrangement, sealing system, and one or more safety devices. The goal is a smooth, finely controllable rotational movement with high load capacity and long service life.
Hydraulic motor and gearbox
Orbital or axial-piston motors are commonly used because their high starting torque allows fine metering even under load. Torque is amplified via a planetary gearbox to provide the required force at the tool head. A matched rotary bearing absorbs radial and axial loads that occur during gripping, cutting, or splitting.
Rotary union and hose routing
The rotary union enables pressure-tight media routing during 360° movement. As a result, cylinders, grapples, or splitting wedges remain constantly supplied without hoses becoming twisted. Clean hose routing reduces friction, avoids kinks, and increases operational safety.
Valves and protective functions
Shock and relief valves protect against pressure spikes that can occur during sudden load changes. Non-return and counterbalance valves stabilize motion, minimize overrun, and improve precise positioning of tool blades or splitting wedges.
Control and sensitivity
The rotation function can be actuated via on/off valves or controlled proportionally. Proportionality supports precise alignment of the tool, which is particularly important in selective concrete demolition or when cutting along edges and reinforcement.
Benefits in concrete demolition and special demolition
Hydraulic rotation makes it possible to apply tools optimally without repositioning the carrier. This is especially relevant in concrete demolition, during the targeted removal of individual structural elements, or in special demolition when adjacent structures must be protected.
- Exact positioning of the concrete demolition shears at edges, columns, or beams
- Clean placement of cutting tools on reinforcing bars, profiles, and tanks
- Reduced collateral damage thanks to a controlled attack angle
- Shorter cycle times, as regripping and repositioning are needed less frequently
- Increased safety and ergonomics through smooth, predictable movements
Concrete demolition shears: precise alignment of the blades
With concrete demolition shears, hydraulic rotation facilitates parallel placement of the blades against the concrete surface. Thanks to 360° orientation, reinforcement can be exposed in a targeted way and edges can be approached cleanly. This reduces shock loads and lessens the effort required for rework.
Applications: from strip-out to natural stone extraction
The advantages of hydraulic rotation are evident in numerous Darda GmbH applications:
- Strip-out and cutting: Sensitive alignment of combination shears, multi cutters, steel shears, and tank cutters in confined spaces and hard-to-reach areas.
- Concrete demolition: Selective removal of elements with concrete demolition shears; rapid rotation from one component to the next without repositioning.
- Rock breakout and tunnel construction: Rotational alignment supports targeted tool placement at cracks and natural planes of weakness.
- Natural stone extraction: With stone and concrete splitters as well as stone splitting cylinders, rotation helps orient wedges, borehole axes, or split faces correctly.
- Special operations: Where cutting on vessels, profiles, or special materials is required, rotation facilitates controlled adjustment of the attack angle.
Hydraulic power packs and control of the rotation function
Darda GmbH hydraulic power units for rotation provide pressure and flow. For the rotation function, proper matching is essential: the flow rate influences rotational speed, and system pressure determines torque. Proportional valves offer soft start and precise controllability.
Parameter tuning in practice
- Flow rate: sufficient for the desired rotational speed without over-supplying the valve
- Pressure level: matched to the required torque with effective pressure limitation
- Return and case-drain routing: designed for low pressure to avoid heating and cavitation
- Valves: shock and anti-cavitation valves for protection under load changes
- Control logic: sensitive proportional control for accurate tool alignment
Selection criteria for rotators and rotary drives
- Torque and holding torque: matched to maximum tool resistance
- Rotational speed: finely metered, fast enough for short cycle times
- Axial/radial loads: bearing design for real operating forces
- Endless rotation or limited slewing range: depending on the application
- Gear backlash and positioning accuracy: for a clean cutting or splitting approach
- Seals and protection against contamination: robust against dust, water, and abrasion
- Interfaces: mechanical flanges, hydraulic ports, valve technology
- Weight and installation space: ergonomic and suitable for the load capacity
- Service accessibility: lubrication points, filters, wear parts
Safety and operation
Safe work requires a smooth, controlled rotational movement. Pressure spikes should be absorbed by suitable valves, case-drain oil must be routed correctly, and hose routing must prevent twisting and kinking. Loads should be gripped to avoid unintended torque peaks. In practice, a gentle ramp-up of rotation and careful alignment immediately before cutting, breaking, or splitting has proven effective.
Maintenance and service life
- Regular visual inspection for leaks, damage, excessive play
- Cleanliness at the rotary union and connections; protect sealing surfaces
- Observe oil condition and filtration to reduce wear in motor and gearbox
- Lubrication according to specifications, if lubrication points are present
- Monitor operating temperature, avoid overheating
Typical wear and fault symptoms
- Overrun and “creeping” despite neutral position: indicator of leakage or valve seat issues
- Decreasing torque: possible wear in the motor or gearbox
- Increased axial/radial play: check bearings
- Rough running or noise: check filtration, oil condition, and valves
Troubleshooting and practical remedies
- Check hydraulic supply: pressure, flow rate, temperature, filter condition
- Test valve function: calibrate proportional valves, check shock valves
- Rule out mechanical blockages: ensure the tool is freely movable
- Check hose and case-drain routing: eliminate backpressure and kinks
- Inspect seals, bearings, and gearbox: replace wear parts as needed
Distinction: rotation and slewing
Hydraulic rotation enables endless 360° rotation, while slewing drives cover a limited angular range. In demolition practice, rotation is used to align tool blades or gripping jaws precisely; slewing serves to set the angle of the entire head. With concrete demolition shears, the combination of rotation and the linear jaw movement is particularly effective. With stone and concrete splitters and stone splitting cylinders, rotation chiefly supports exact placement and alignment along the intended split line.
Practical tips for efficient use
- Pre-positioning: first grip or set the workpiece steadily, then fine-rotate
- Use short, metered rotation pulses to align the blades precisely to edges
- Route hoses without tension; avoid twisting
- Allow torque reserves for changing materials and adjust speed accordingly
- Regularly check for play and overrun to ensure lasting precision