ACCURACY GREATER THAN WITH GEODESIC SURVEYS
Pendulums are designed to accurately measure the relative internal horizontal displacements of points along a true vertical line
The direct pendulum consists of a wire suspended from the upper point and a reading station fixed to the structure at the lower point. The wire is tensioned by a suspended weight submerged in a damper tank.
The fixed end of the inverted pendulum is grouted at the lower point of the system. A float tensions the wire vertically. When anchored to a fixed point in the foundation, it measures absolute displacement of points along the wire.
The monitoring of the wire position for both direct and inverted pendulums can be done manually and/or electrically with a remote readout unit (ref: Model RxTx Telependulum – see separate brochure). The method of reading depends upon the concept of monitoring, the expected values of movements, and the accuracy required.
Manual Reading Options and Interpretations
A) Sighting reading table Model 76
To take a reading, the operator aligns the cursors with their respective sights and with the pendulum wire. The positions of the cursors are read directly off the scale and the vernier cursor. The readings are converted to wire displacement values using the chart provided with each reading station.
B) Optical coordinoscope Model MVR
The setup consists of a reference base permanently installed at the reading point. The coordinoscope is then installed on its reference section respectively at X and Y axes on the base frame. Measurements are taken by focusing or aiming the lens at the pendulum wire and by reading the current lateral displacement on the vernier.
Stainless steel or invar wire
Upper hook and vee-shaped guide bracket
Wire tensioning weight and hook
Wire (same as for direct pendulum)
PVC float and float tank assembly
Reading station component
Stainless steel table
(includes scales, cursors, sights and chart for evaluating wire position)
500 x 500 mm