European contractors are adopting a new French system for the construction of vibrated, cast in place piles. The system is said to be much fast than existing methods; it also allows load-carrying capacities to be doubled. The piles are constructed by first driving a casing into the ground with a ring shaped, vibratory pile driver. The casing can be between 20 inches and 5 feet in diameter. Soil is excavated simultaneously during driving by means of a special grab. The casing is then filled with concrete and finally withdrawn. Vibrations transmitted to the wet concrete during withdrawal result in a complete "shaking-in" key with the surrounding soil. Equipment is mounted on a 4 by 6 vehicle. The driving mast is hydraulically raised vertically over the pile location, and a pile can be excavated within 10 minutes after the truck reaches the site. The first of thin walled casing sections is fitted with a cutter head and a patented locking device for the excavating grab. The lock ensures that both the cutter head and the grab are flush and enter the soil together. During the driving operation, the lock automatically releases the grab when it is full, for withdrawal and discharge. Combined driving and excavation compresses the soil to double the load that would otherwise be handled by the grab. Directional vibration is applied to the casing via eccentric-mass flywheels. Power is supplied by the truck engine via synchronous hydraulic motors. Frequency can be adjusted within seconds to suit soil conditions. Range lies between 800 to 1700 rpm. De-synchronizing the motors exerts a turning movement on the casing that allows driving through even the most difficult soils. A patented clamping chuck, consisting of inflated hard rubber tubes, retains the casing within the vibratory unit. The chuck allows immediate clamping and release.