Test probe measuring hardness of underground strata - is housed in vertical rod pressed into ground with inner tube applying pressure to transducer

摘要

The transducer head (1) has a conical point (2) which is in contact with a force converter (3), e.g. a strain gauge. The head has an internal screw thread (5) which mates with an external screw thread (6) on the lower end of an outer tube (7). Within the outer tube is a thin walled inner tube (11), through which the transducer cables can run. At the top of the probe, a pressure application block (14) bears onto the upper end of the inner tube. The upper end (13) of the inner tube is also screwed (10) to the outer tube. The pressure which stresses the transducer is applied via the inner tube, which is protected from the surrounding earth by the outer tube. The measurement is thus unaffected by the effects of friction between the tube and the surrounding earth. The probe is withdrawn by lifting the block, the claws (15) of which pull on the outer tube, thus ensuring that traction is not applied to the inner tube.