Wedge lock systems
The wedge lock system belongs to the high-end products in the area of mechanical securing elements. It comes under anti-rotation lock and can be found in various designs.
The screw and the part to be joined remain firmly connected. The screw connection remains stable, the preload force is almost retained and the fastener stays in its initial position. It is recommended to add an additional safety element, especially with critical screw connections, which are to withstand extreme vibrations, changing forces or dynamic loads.
The retaining function of the washers is due to four factors: difference in hardness, difference in angle, difference in friction and difference in preload.
Difference in hardness
As the surface of the wedge-lock washer or ring-lock washer is harder than that of standard screws, the radial ribs on the outer sides of the washer cut into the mating material. This creates a positive-lock connection when the screw assembly is tightened.
Angle difference α > β
The specific angle of inclination of the wedge-shaped surfaces on the washer creates a self-locking effect should the screw come loose of its own accord.
Difference in coefficient of friction µa > µi
The wedge-shaped sections at the parting lines between the two washer halves have a significantly lower coefficient of friction than the toothed outer surface of the washers. As a result, any rotational movement always causes movement between the two washer halves and not between the disc and the workpiece.
Preload difference
If the wedge-locking washer expands due to a loosening movement, this leads to elongation of the screw and thus to an increase in the preload force. This creates a "self-locking" of the screw connection.
Hexagon head screw secured at both ends in a through-hole
Hexagon bolt secured in a blind hole
Cylinder head bolt secured in a countersunk hole
No locking function when used in combination with washers
Example of the use of wedge-locking nuts
Released factory standards:
- Siemens AG: KUN607.07
- Enercon GmbH: MK 06 007-1
- Alstom Transport AS: DTRF15021 - Appendix 5
- Deutsche Bahn AG/DB Systemtechnik GmbH: general approval
- Knorr-Bremse
- Hübner
Institutes:
- German Institute for Building Technology: general building authority approval (abZ) No. Z-14.4-702
- TÜV Rheinland: RoHS approval in accordance with Directive 2002/95/EC
- TÜV Süd: Approval of the HEICO-LOCK® wheel lock nut
- DNV GL: Whitness tests of the HEICO-LOCK® wedge lock washer
- DIBt: ETA-20/0075 for HEICO-LOCK® wedge lock washer narrow & wide shape in steel zinc flake
Our in-house product series W.TEC® represents our carefully curated selection of products that stand out due to their excellent functionality and top class quality. Each product has been developed with the highest quality standards in order to meet the requirements of the industrial customers. This combination of precision and performance makes the products of our W.TEC® series price and performance champions.
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