The nominal load is a central criterion for planning, selection, and safe use of hydraulic tools and attachments in concrete demolition, interior demolition, rock demolition, and natural stone extraction. It defines which load a component, a tool, or a lifting accessory may safely carry under defined conditions. For applications with concrete crushers, stone and concrete splitters, combination shears, multi cutters, steel shears, or tank cutters from Darda GmbH, the nominal load determines how forces, weights, and cutting or splitting operations are safely controlled.
Definition: What is meant by nominal load
Nominal load is the manufacturer-specified permissible load of a component or device under normatively defined operating conditions. Terms such as load-bearing capacity, allowable working load (WLL), or Safe Working Load are often used for this. The nominal load takes into account common safety margins, material properties, manufacturing tolerances, and typical dynamic influences. In the context of hydraulic demolition and cutting technology, the nominal load describes, for example, the maximum permissible load of a lifting accessory, the limit load of a lifting point, the permissible attachment mass for a carrier machine, or—functionally—the nominal force of a cylinder, the splitting force of a stone splitting cylinder, and the cutting or pressing force of a concrete crusher. It is important to clearly distinguish between load (weight or force from the application) and self-weight (mass of the device), as both add up in the system.
Technical context: nominal load in demolition, hydraulics, and carrier technology
In practice, several nominal loads come together in deconstruction tasks: the load-bearing capacity of lifting accessories, the permissible attachment load of the carrier machine, the nominal hydraulic force (operating pressure and piston area), and the load-bearing capacity of the structural element or rock mass being worked. With concrete crushers, the available cutting and pressing force determines which component thicknesses, reinforcement ratios, and concrete strengths can be safely processed. With stone and concrete splitters, splitting force and wedge geometry govern the attainable split width and the controlled crack propagation in rock or concrete. The nominal load of the lifting accessories defines how prefabricated segments or detached components can be safely held, rotated, or set down. At the same time, permissible attachment weights and the hydraulic data of the carrier (operating pressure, flow rate) limit the combination of tool and working method. Only when all components are operated within their nominal load range are safety, process quality, and equipment service life ensured.
Calculation and derivation: from pressure and geometry to nominal load
For hydraulic tools, the available force results from the product of operating pressure and effective piston area. From this, nominal forces for cylinders, wedges, and shears are derived. Example: A hydraulic pressure of 400 bar corresponds to 40 N/mm². If this pressure acts on a piston area of 2 000 mm², a theoretical force of 80 000 N (80 kN) is available. Inefficiencies, leverage, friction, and safety factors reduce the usable force down to the permissible nominal load. In concrete crushers, the resulting cutting and pressing force is influenced by the kinematics of the jaw arm and the geometry of the blades; in stone and concrete splitters, wedge angle and spreading surfaces determine both the peak force and the force distribution in the borehole. Therefore, nominal load specifications must always be read in conjunction with the associated operating parameters: pressure range, flow rate, opening width, component thickness, material grade, and permissible attachment weights.
Nominal load in typical Darda GmbH products and functions
Depending on the type of tool, the nominal load reflects different technical characteristics:
- Concrete crushers: nominal load as available pressing and cutting force, combined with information on opening width, permissible concrete and steel thickness, and recommended application areas in concrete demolition and specialized deconstruction.
- Stone and concrete splitters including stone splitting cylinders: nominal load as splitting force at the wedge tip; decisive for borehole diameter, split width, and controlled crack formation in rock, concrete, or natural stone.
- Hydraulic power packs: nominal load as permissible operating pressure and flow rate; these limit the maximum retrievable cylinder force and thus tool performance.
- Combination shears, multi cutters, steel shears, tank cutters: nominal load as cutting force or permissible material thickness and strength; relevant in interior demolition and cutting of sections, sheets, pipes, and reinforcement.
For the overall system, the permissible attachment weights on the carrier and the load-bearing capacity of the lifting and load-handling accessories must also be observed. This prevents the sum of self-weight, payload, and dynamic components from exceeding the nominal load of any subsystem.
Fields of application: significance of nominal load in the workflow
Concrete demolition and specialized deconstruction
When selectively removing components, correctly chosen nominal loads ensure that concrete crushers cut component thicknesses within the intended ranges and that detached elements are guided with suitable lifting accessories. Impact loads due to sudden breakage are cushioned by appropriate safety factors and gentle machine movements.
Interior demolition and cutting
In interior demolition, cutting force and permissible material thicknesses determine which sections, tanks, or pipework can be processed. For tank cutters, the nominal load refers to cutting capacity and operating pressure, while lifting and securing accessories require their own load-bearing capacity.
Rock demolition and tunneling
Stone and concrete splitters enable controlled crack formation without blasting. The nominal load of the splitting cylinders defines which rock or concrete strengths can be processed efficiently. Drilling pattern, borehole depth, and wedge geometry are matched to the available splitting force.
Natural stone extraction
When loosening blocks, splitting forces, wedge travel, and the load-bearing capacity of lifting accessories are decisive for extracting the raw blocks. The nominal load of lifting points on blocks or spreader beams must not be undershot.
Special operations
In situations with limited installation space or special boundary conditions (for example elevated temperatures, moisture, abrasive dusts), nominal loads may effectively be reduced. A conservative design and careful working method are advisable here.
Distinction: nominal load, load-bearing capacity, allowable working load
The nominal load is a manufacturer-specified limit load under defined conditions. Load-bearing capacity in construction often describes the design load of structural components. The allowable working load denotes the load that a lifting accessory may safely carry in normal operation. All three terms are related, but not identical. In application, it is crucial which metric refers to which part of the system: tool, lifting accessory, carrier, or the structure or rock mass.
Planning and selection: a systematic path to the correct nominal load
- Determine load: self-weight of the workpiece, additional loads (reinforcement, attachments), friction and clamping loads.
- Account for dynamics: movements, impact loads, vibrations; choose suitable safety factors.
- Select the tool: choose concrete crusher, stone and concrete splitter, or shear according to nominal force, opening width, and material properties.
- Verify hydraulics: align operating pressure and flow rate of the hydraulic power unit with the tool’s requirements.
- Size the carrier and lifting accessories: check permissible attachment weights and the load-bearing capacity of chains, slings, or spreader beams.
- Assess component behavior: concrete strength, reinforcement ratio, crack condition, support; in rock, jointing and bedding.
- Document and label: record nominal loads, settings, and inspection statuses.
Influencing factors that can reduce usable nominal load
- Deviating hydraulic values: too low or fluctuating operating pressure, insufficient flow rate.
- Wear and condition: dull blades, damaged wedges, leaks, worn bearing seats.
- Temperature and medium: viscous oil in cold conditions, overheating under continuous load, contamination.
- Unfavorable kinematics: unfavorable leverage on the component, lateral forces, jamming.
- Component properties: higher reinforcement ratio, higher concrete or rock strength than assumed, existing stresses.
- Environment: confined conditions, restricted visibility, difficult lifting points.
Marking, documentation, and practical rules
Nominal loads are usually permanently marked on tools and lifting accessories. These include details of operating pressure, maximum force, opening width, permissible material thickness, or attachment weight. In practice, clear assignment of components, regular visual inspections before starting work, and a low-stress operating method have proven effective. If the workflow changes (for example a different component cut), update load assumptions and reconcile nominal loads again.
Testing and maintenance
Periodic inspections, maintenance according to manufacturer specifications, and the condition of cutting and splitting tools have a direct effect on safe use within the nominal load. Inspection intervals should be aligned with usage intensity and environmental conditions. Legal frameworks and technical rules may vary by country and application scenario; application is always carried out on one’s own responsibility and in accordance with recognized engineering standards.
Typical misinterpretations and how to avoid them
- Nominal load is not a guarantee for every situation: it applies only under the specified conditions. Deviations require reserves.
- Forces add up: self-weight, payload, and dynamic components act together.
- Tool performance is system-dependent: without matching operating pressure and flow rate, the nominal force will not be reached.
- Material influence is decisive: higher strengths of concrete, steel, or rock can significantly increase the required force.