The Crab system

Noeud_Crab_clavet_flechThe Crab system consists of a self-locking wedge key attached to a clamp.
Once a ledger is in contact with a clamp, the wedge automatically pivots for instant assembly. A single blow to the wedge ensures the strength of the connection.
When wedging is carried out along the main axes, all ledgers are guaranteed to be installed at a right angle.

positions_moise_diagosA ledger may, though, be fitted in any direction: there are no dead angles.
The Crab knot allows simultaneous fitting of 8 components: 4 ledgers and 4 diagonals.

compatibilitéThe Crab system allows a ledger to have a single centre distance, irrespective of post diameter (49, 57 or 60 mm). This feature means that identical ledgers, diagonals and planks are used on all of our systems fitted with the Crab knot.

The Crab system is used on Multicrab scaffolding using 49 mm diameter tubes, on Crabétai shoring using 57 mm diameter tubes and on Crabtour and Touréchaf shoring using 60 mm diameter tubes.
The use of common scaffolding and shoring components makes equipment management easy.
The Crab system is able to mix and match posts with different diameters according to the load-bearing requirements. For example, the Crabétai 57 mm diameter post can be used on the lower part of high-rise scaffolding, whilst upper levels are erected using the Multicrab 49 mm diameter post.