Rod Extensometer

Rod Extensometer

More Information


Australia Tel: +61 (0)3 8720 6700
Indonesia Tel: +62 21 3040 4422
New Zealand Tel: +64 (0)7 850 2610
South Africa Tel: +27 (0)10 900 2055


The Model 4000 Rod Extensometer is a simple to install unit consisting of up to 6 spring steel rods anchored at measurement points within the borehole. As the anchors move the displacement variation is measured with respect to the instrument head. The measurement rods are sleeved in polyethylene tubing. Coiled neatly in a 1m coil, they are simple to install and can be read using either a dial gauge (in the case of the manual head) or a digital indicator (when the remote reading head is used). For remote reading Applications, a low cost, accurate transducer head can be used.


Measurement of settlements, displacements and deformation in:

  • Tunnelling
  • Open cut mines
  • Dam construction
  • Underground mines
  • Large excavations
  • Construction control


  • Low cost
  • Complete instruments supplied ready for installation
  • One to six anchor positions for varying ground conditions
  • Compact design, for ease of transportation
  • Potentiometric transducer head protected inside borehole
  • Direct connection to linear transducers, no racks and pinions.
  • Able to be connected to datalogging systems

Specifications of the Model 4000 Rod Extensometer

  • Range of extension: 150mm
  • Accuracy: 0.1mm
  • Maximum number of anchors: 6
  • Head material: Stainless Steel
  • Protective sheath material: 25mm LDPE
  • Nominal borehole diameter:100mm
  • Dimension (head): 51mm, 520mm long
  • Dimension (Protective sheath): 29mm
  • Anchor: 40mm

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