ST-Rods – the (un)folding CPT string!
Why create ST-Rods when we already have AR-Rods and 2R-Rods? Because A.P. van den Berg ST-Rods are something quite different! They can be in 1 of just 2 states, twisted or untwisted, and it takes very little to transform them from one state to another. Untwisted, the ST-Rods behave a bit like a pearl necklace and can be easily folded onto a reel. Once twisted, the rods form a solid CPT string with a push/pull/buckle performance equal to a string of standard AR rods.
Because the rods have a self seeking bayonet thread (pictures above) they close effortlessly and require just a final, short, single twist to become firmly interlocked, hence the name SingleTwist-Rods. Having rods with this patented design, the transformation process during CPT pushing as well as pulling is like a natural flow and done almost entirely mechanically, making it very robust indeed. Click here for a short movie.
The Folder, a reel with a single layer of rods, can be supplied with a diameter from 6 rods/winding upwards and with a width starting from a winding or two. This allows for folders holding between 5m and 75m of CPT string, depending on the application. In case of string damage, each full winding can be easily replaced with a spare one. And between jobs, one folder can be exchanged with another, provided they have the same diameter.
All it takes to put together an automated CPT system, i.e. one that performs a full CPT and a subsequent complete reel-in of the string on a single operator command, is a Folder, a Twister and a Sprocket, a wheel to connect the two. This very compact SingleTwist™ system (picture above) can be mounted on virtually any A.P. van den Berg pusher, including onshore COSON penetrometers and ROSON seabed systems.
Needless to say that, since the ST-Rods come fitted with an Icone cable, you enjoy the full bandwidth of A.P. van den Berg’s digital bus and you are compatible with all Icone sizes and all available click-on modules. If you wish to see a solid CPT string (un)fold in front of your eyes, please contact us for an appointment in Heerenveen. A full-blown 10 ton ROSON-ST awaits you there as well as - of course - a cup of coffee!