A fitting piece is a precisely manufactured intermediate or spacer component used in demolition, cutting, and drilling applications to compensate dimensions, center components, transfer loads cleanly, or make interfaces compatible. In conjunction with Darda GmbH hydraulic attachments and handheld tools—such as concrete demolition shears, rock and concrete splitters, combination shears, or steel shears—fitting pieces ensure a precise fit, improve process stability, and support a reproducible, safe way of working on the construction site, in rock, and in tunnels.
Definition: What is meant by fitting piece
A fitting piece is a dimensionally accurate, often ground component used as an adapter, compensation or spacer between two parts. It performs functions such as centering, aligning, spacing, reducing/increasing connection dimensions, or defining a support and load-transfer surface. Fitting pieces can be installed permanently or temporarily, are usually made of steel or aluminum, and are used at mounting points, in bearings, hydraulic connections, tool interfaces, and drill-hole environments.
Function and application scope of fitting pieces
In practice, fitting pieces perform several tasks: they compensate for manufacturing and installation tolerances, protect adjacent components, ensure the correct installation position, and provide defined load transfer. In concrete demolition and special deconstruction as well as in rock excavation and tunnel construction, they help position Darda GmbH tools safely—for example, when applying a concrete demolition shear to load-bearing members or inserting a rock and concrete splitting cylinder into a borehole. They are also used in strip-out and cutting to set cutting gaps, jaw or blade clearances, and to adapt to varying material thicknesses.
Designs and materials
Fitting pieces differ by design, material, and tolerance class. Selection depends on function, load, and environmental conditions.
Typical designs
- Spacer rings and shims for height or thickness correction
- Adapter plates and intermediate plates to adapt mountings
- Centering bushings and sleeves for precise alignment
- Reducers/expanders for connection diameters on hydraulic lines
- Support and protection plates to protect concrete edges and borehole mouths
Materials and surfaces
- Quenched and tempered steel for high compressive and impact loads
- Tempered or hardened shims for wear-intensive bearing points
- Aluminum or stainless steel where weight, corrosion protection, or media resistance are paramount
- Surface treatments such as bluing, galvanizing, or nitriding to reduce wear and corrosion
Fitting pieces in conjunction with rock and concrete splitters
When splitting concrete or natural stone, boreholes with defined diameter and depth are produced. Here, fitting pieces can serve as centering sleeves or protection rings to guide the splitter cylinder precisely in the borehole and protect the borehole mouth from spalling. Spacer shims make it possible to compensate for small deviations in borehole depth so that the wedge of the splitting cylinder operates in the optimal position. This improves splitting performance, reduces edge chipping, and lowers stress on both tool and material.
Fitting pieces on concrete demolition shears, combination shears and Multi Cutters
On gripping and cutting tools, fitting pieces ensure the correct geometry: shims on pivot bolts set the defined jaw or blade clearance; intermediate plates on mountings adapt the tool to carrier machines or handling systems. A cleanly adjusted cutting or gripping gap reduces wear on blades and jaws, improves cut quality, and supports an even load distribution over the entire stroke.
Hydraulic fitting pieces: adapters and transitions
In hydraulic systems, fitting pieces connect different connection geometries, threads, or nominal sizes. Decisive factors are permissible operating pressure, sealing type, and media compatibility. Adapters and reducers must match the pressure rating of the hydraulic power pack and the connected tools to avoid pressure losses and leaks. Important is a clean, stress-free installation: sealing surfaces must not be damaged, and approved sealing compounds must be used and applied in the correct quantity.
Selection criteria and design
The design of a fitting piece is guided by mechanical, geometric, and operational requirements. The goal is safe, repeatable function without impermissible deformation or play.
Relevant criteria
- Function: centering, spacing, adapter function, protection
- Load case: compressive, shear, bending, and impact loads
- Dimensions and tolerances: fit, flatness, parallelism
- Material and heat treatment with regard to strength and wear
- Environment: moisture, corrosion, temperature, dirt
- Hydraulics: pressure rating, sealing concept, compatible media
Installation and practice
Proper installation ensures full effectiveness of the fitting piece and protects adjacent components.
- Clean components; remove burrs and damage on support or sealing surfaces.
- Check dimensions (thickness, runout, fit). Observe identification and installation orientation.
- Insert the fitting piece without stress; ensure full-surface contact of the bearing faces.
- Tighten fasteners to the specified torque; re-tighten screws/bolts if necessary.
- Perform a functional test (stroke, gripping/cutting clearance, leakage test in the hydraulics).
- Update documentation (thickness, position, date) to keep later settings reproducible.
Safety and diligence
Fitting pieces affect load transfer and thus operational safety. Installation and use should follow the applicable technical rules. Stated permissible loads, torques, and pressure ratings must be observed. Changes to tool geometries, mountings, or hydraulic connections should be professionally assessed and documented. Legal requirements may vary by country and must be observed for the specific application.
Maintenance, wear, and replacement
Fitting pieces are wear parts, especially when they act as support or spacing surfaces within the load path. Regular visual and dimensional inspections (loss of thickness, plastic deformation, notches, corrosion) are advisable. Heavily loaded shims or protection rings should be replaced in good time to prevent consequential damage to tools or components. In hydraulic systems, sealing surfaces and threads must be checked each time connections are separated or made.
Common mistakes and how to avoid them
- Incorrect thickness/fit: leads to stresses and uneven load distribution.
- Inappropriate material: insufficient strength or corrosion resistance.
- Damaged support or sealing surfaces: promote play, settling effects, or leaks.
- Unclear documentation: makes reproducible settings on concrete demolition shears or splitting cylinders difficult.
- Incompatible hydraulic adapters: risk of pressure losses and seal failure.
Application examples in the fields of use
Concrete demolition and special deconstruction
Fitting pieces define gripping and cutting geometries on concrete demolition shears, secure adapter plates on mountings, and protect concrete edges during positioning. Spacer rings compensate tolerances so jaws close in parallel and the cut runs true.
Strip-out and cutting
With varying component thicknesses, shims enable repeatable settings. Intermediate plates support precise positioning of combination shears or Multi Cutters on handling systems.
Rock excavation and tunnel construction
Centering sleeves guide splitting cylinders in the borehole, minimize edge spalling, and improve directional accuracy during splitting. Protection rings at the borehole mouth prevent damage at the exit zone.
Natural stone extraction
Fitting pieces provide defined bearing on uneven rock surfaces and support a straight split pattern through precise cylinder guidance.
Special applications
For atypical geometries or limited installation space, special fitting pieces are used—for example, particularly flat spacer plates or profiled protection pieces that deliberately redirect forces and protect adjacent surfaces.
Quality assurance and traceability
Marking fitting pieces (thickness, material, batch) facilitates traceability and spare parts management. Inspection records of dimensions and surface condition as well as photos of the installation situation support consistent use over the service life of Darda GmbH tools.